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Hist. Phil. Life Sci., 34 (2012), 341-360
The relationship between microevolution
and the structure of the extended synthesis
Guillermo Folguera and Olimpia Lombardi
CONICET – Facultad de Ciencias Exactas y Naturales
Universidad de Buenos Aires
Espinosa 423 108, C.P. 1405, Ciudad Autónoma de Buenos Aires, Argentina
AbstrAct - This article focuses on the relationship between microevolution and
macroevolution. The main purpose is to argue that up to the present time in the consolidation
of the evolutionary synthesis, macroevolution has been always conceived as dependent on
microevolution. Such dependence was very clear in the synthesis, but seems to have been left
aside by later authors. Nevertheless, we will show that the criticisms of the synthesis since
the decade of the 1970s did not modify that general trend: the new perspectives reproduced
the dependence of macroevolution on microevolution by means of strategies different than
those appealed to by the traditional synthesis.
Keywords - Altenberg 16, evolutionary synthesis, Gould, macroevolution, microevolution
Introduction: macroevolution and the promise of an extended syn-
Since the 1930s, the disciplines grouped together under the biological
synthesis played different roles in that dominant theoretical framework.
Whereas some of them introduced mechanisms of evolutionary change,
others played only a descriptive role in evolutionary biology. According
to Arthur (1997), population genetics, evolutionary ecology, and classical
genetics belong to the ﬁrst group; the disciplines of the second group,
such as paleontology and comparative anatomy, are conﬁned to describ-
ing phenomenological patterns (see also Ghiselin 1980). There is also
a third group of “forgotten” disciplines, like embryology and develop-
mental genetics, which did not play a relevant role in the traditional syn-
thesis. In this context, the evolution of populations, or microevolution
(mev), ﬁnally turns out to be conceived as the dominant area of evolution,
356 Guillermo FolGuera and olimpia lombardi
which relegated the evolution of higher taxa, or macroevolution (Mev),
to a secondary position (see Bowler 1998; Folguera 2010; Folguera and
di Pasquo 2008).
Over the past years, the idea of an extension of the biological synthe-
sis increased its strength within the evolutionary community (Callebaut
2010; Grantham 2004; Love 2010; Okasha 2005). This extension ﬁnds its
roots mainly in the expansion and consolidation of Evo-Devo, genomics,
and macroevolution (Ioannidis 2008; Love 2003; Scott 2002), and began
to be related with certain philosophical problems, including the ques-
tion about the autonomy of the different areas of knowledge, as well as
the disciplinary relationships within the “extended” biological synthesis
itself (Callebaut 2010; Love 2010; Rosslenbroich 2009; van der Steen
1993). Some authors have suggested that the extension of the biological
synthesis might lead to the consolidation of a pluralistic framework in
evolutionary biology (Delisle 2009; Mitchell 2002; Sterenly 1996).
In this article, we will focus on the relationship between mev and Mev.
Like Love, we will use “the interplay between the conceptual and disci-
plinary levels as a heuristic tool [...] assuming that the conceptual level
typically has implications for the disciplinary level” (Love 2003, 312).
Our main purpose is to argue that since the consolidation of the evo-
lutionary synthesis up to the present, Mev has been always conceived as
dependent on mev. However, such dependence was expressed through
very different strategies. In general terms, the evolutionary synthesis
proposed a direct dependence of Mev on mev, although with some signiﬁ-
cant variants in the arguments of the different authors. But the criticisms
to the synthesis since the decade of the 1970s did not modify that general
trend: the new perspectives reproduced the dependence of Mev on mev
by means of strategies different than those appealed to by the traditional
For this purpose, the present paper is organized as follows. In the sec-
ond section, we will point out certain similarities and differences among
the stances of the main scientists of the biological synthesis, Theodosius
Dobzhansky, Sewall Wright, George Gaylord Simpson, and Ernst Mayr.
In the third section, the criticisms leveled against the synthesis’ concep-
tion of the relationship between mev and Mev since the 1970s are critically
reviewed. In the fourth section, we will analyze the role played by that
relationship in the new extended synthesis proposed by “Altenberg 16.”
In addition, we will analyze the relationship among “problem agendas,”
structure and pluralism in the biological synthesis, on the basis of the
proposal of Alan C. Love. In the last section, we will offer some consid-
erations about the differences among the roles played by the disciplines
belonging to the new synthesis and the consequences of this difference
357Microevolution and Macroevolution
over the problem of the unity of science. Finally, on the basis of the
previous considerations, we will argue that the critics of the traditional
synthesis could not, nevertheless, free themselves from the idea of the
priority of mev over Mev.
The relationship between microevolution and macroevolution in the
In the light of our main purpose, the consideration of the main opin-
ions about the relationship between mev and Mev in the traditional syn-
thesis acquires a particular relevance. The most inﬂuential scientists of
the synthesis agreed about the following points: i) fossil records were
viewed as legitimate phenomena to be accounted for by evolution; ii)
population genetics was placed at the “core” of the biological synthesis;
iii) paleontology was considered unable to answer the question about
evolutionary mechanisms (Depew and Weber 1996; Mayr 1982); and
iv) microevolutionary mechanisms were extrapolated (partially or com-
pletely, depending on the researchers) to the explanation of macroevo-
lutionary phenomena (Bock 1970; Bowler 1998; Eldredge and Tattersall
1986; Thompson 1983), due precisely to the theoretical inability of the
studies of Mev to contribute to the understanding of evolutionary pro-
cesses (Arthur 1997). Nevertheless, these agreements did not lead to a
convergent view about the particular dependence of Mev with respect to
One of the most inﬂuential perspectives about the relationship be-
tween mev and Mev was that proposed by Theodosius Dobzhansky,
who introduced some relevant differences between those two domains
(Dobzhansky 1965). For instance, while microevolutionary processes
are reversible, macroevolutionary processes are irreversible. To illustrate
this case, Dobzhansky contrasted the resistance of a certain bacteria to
an antibiotic with the irreversible evolution of Homo sapiens. For the
author, this difference is due to the mechanisms of genetic variation: the
number of genes responsible for macroevolutionary processes may be
thousands, whereas the genes involved in microevolution are very few.
Another difference is related to the determinism of the processes, which
was conceived both in epistemic and in ontological terms. According
to Dobzhansky, the responses of populations to environmental changes
are predictable; on the contrary, in the case of macroevolution there are
multiple possible responses. This means that indeterminism in evolution
is due not to a mere lack of information, but to ontological causes. The
third difference between mev and Mev is related to a methodological as-
358 Guillermo FolGuera and olimpia lombardi
pect. Dobzhansky pointed out that, by contrast to mev, we have no access
to direct evidence of Mev.
Nevertheless, these differences did not cancel the assumption of a
priority of mev over Mev. In fact, the emphasis on population evolution
was one of the main features of Dobzhansky’s evolutionary thought;
that is, population was considered the unit of evolution (Dobzhansky
1937; 1951). On this basis, since the decade of the 1920s, Dobzhansky
suggested that almost the entire knowledge about evolution could be
derived from the analysis of the biological distribution among and the
variability within populations. This focus on the dynamics of popula-
tions can also be recognized in Dobzhansky’s conceptualization of the
speciation process, as resulting basically from genetic isolation of popu-
lations (Dobzhansky 1933).
Another point that deserves to be considered is the degree to which
the researchers of the synthesis accepted the dichotomy mev-Mev. In this
sense, Dobzhansky introduced a third area, mesoevolution, “placed”
between mev and Mev and endowed with speciﬁc features. Although, ac-
cording to Dobzhansky, mesoevolutionary phenomena have higher com-
plexity than microevolutionary phenomena, the difference is neverthe-
less only quantitative and, therefore, mesoevolution must be also studied
by experimental methods.
The evolutionary perspective of Sewall Wright was different than
Dobzhansky’s, since he introduced remarkable modiﬁcations regarding
the importance and the role of the different evolutionary mechanisms.
Wright speciﬁcally analyzed the relationship between mev and Mev in two
articles published at the end of his scientiﬁc career, “Character change,
speciation, and the higher taxa” (1982a) and “The shifting balance the-
ory and macroevolution” (1982b). In these works, Wright presented his
shifting balance theory as “a third option” in the debate about the rela-
tionship between mev and Mev. According to this theory, microevolution-
ary changes are due to the combined action of natural selection and ge-
netic drift, whereas the action of genetic drift is an important factor for
the modiﬁcation of the genetic frequency in a population, the “motion”
from a “peak” representing a high value of ﬁtness to a new “peak” is due
to the intense effect of natural selection (see Ridley 2003). Nevertheless,
the two mechanisms have relevant effects not exclusively on microevolu-
tion. Genetic drift causes changes not only in the mev domain, but also
in other taxonomical levels, in particular the intensity and relevance of
the action of genetic drift is higher for Mev. On the other hand, selection
might also operate at different scales. There might be selection acting at
a local scale and, in addition, another selection acting among different
localities at higher scales (Wright 1982b).
359Microevolution and Macroevolution
Another inﬂuential position about the relationship between mev and
Mev was that maintained by George Gaylord Simpson. Certainly, this pa-
leontologist was one of the scientists who became more involved in this
problem and its consequences. One of his most relevant contributions
was to conceive the possibility of a qualitative difference between the
two levels of evolution.
Macro-evolution involves the rise and divergence of discontinuous groups,
and it is still debatable whether it differs in kind or only in degree from micro-
evolution. If the two proved to be basically different, the innumerable studies of
micro-evolution would become relatively unimportant and would have minor
value in the study of evolution as a whole. (Simpson 1944, 97)
Certainly, Simpson’s position experienced substantial changes
throughout his life. For instance, in his book Tempo and Mode in Evolu-
tion (1944), he claimed that paleontology is the only scientiﬁc ﬁeld that
can study phenomena at long time scales. In turn, he did not understand
Mev merely as a process that gives rise to genetic groups, e.g., species and
genus. From his perspective, biological evolution has also occurred at
higher levels of the evolutionary hierarchy. Accordingly, he proposed a
“megaevolution” as the domain corresponding to the evolution of higher
taxa. Macroevolution and megaevolution exhibit signiﬁcant differences.
One of them is related to the existence (or not) of gaps in fossil record.
In general, there are no discontinuities in the case of macroevolution,
but they are very frequent and important in the case of megaevolution.
“When the record does happen to be good, it commonly shows com-
plete continuity in the rise of such taxonomic categories as species and
genera and sometimes, but rarely, in high groups” (Simpson 1944, 105).
Two different theoretical interpretations were elaborated to explain
those differences. According to one of them, the absence in fossil record
of intermediate forms is “caused by nondeposition of middle strata or
fossil and to sampling of migrants instead of min lines” (Simpson 1944,
105). For the second interpretation, on the contrary, discontinuities are
real phenomena and not a shortcoming of the fossil record. What posi-
tion does Simpson takes with respect to this problem? On the one hand,
Simpson acknowledged that discontinuities are not due to chance.
In the early days of evolutionary paleontology it was assumed that the major gaps
would be ﬁlled in by further discoveries, and even, falsely, that some discoveries
had already ﬁlled them. As it became more and more evident that the great
gaps remained, despite wonderful progress in ﬁnding the members of lesser
transitional groups and progressive lines, it was no longer satisfactory to impute
this absence of objective data entirely to chance. (Simpson 1944, 115)
360 Guillermo FolGuera and olimpia lombardi
However, in spite of the fact that Simpson admitted the non-random
character of the discontinuities in the fossil record, he denied the idea of
saltational evolution, since it is
…very unlikely, if not impossible, that such major saltations have occurred,
according to present understanding of the genetic mechanism. The most
nearly concrete suggestion of a mechanism adequate for saltation is that of
Goldschmidt (1940), and he quite fails to adduce factual evidence that his
postulated mechanism ever has produced of ever really could produce such an
effect. (Simpson 1944, 116)
Another proposal for explaining the discontinuity of fossil record in
case of megaevolution is based on the existence of changes in mutation
rates. However, Simpson did not accept this explanation.
There is not direct factual evidence for it, however, and it is not necessary
postulate. Moderate mutation rates, more or less like those known in the
laboratory, are necessary: but very high rates, even if there were such rates,
would not sufﬁce to explain these transitions unless also accompanied by the
other special conditions […]. (Simpson 1944, 122)
What is, then, the explanation of those gaps in the fossil record?
Simpson found his answer in certain theories coming from the genetics
of populations, by recalling that the rates of evolution depend on the
According to the theories of population genetics previously summarized, such
unusually high rates of evolution are very improbable in large populations and
are most consistent with the postulate that the transitional populations were
small. (Simpson 1944, 121)
But population size is not the only factor considered by Simpson. For
instance, other factors, like ecological zone, environmental instability,
and individual size, are also very important. Therefore, the gaps observed
in the case of megaevolution’s fossil record are due to “exceptionally
rapid rates” in small populations. In this context, the relevant question
is what are the mechanisms that explain those paleontological records?
According to Simpson, the main mechanism is natural selection, which
allows taxa to rapidly evolve to a new status (Simpson 1944). Therefore,
there is no qualitative difference among the evolutionary mechanisms of
mev, Mev and megaevolution.
Qualitatively similar processes, less only in duration and in the degree of
ecological change involved, seem certainly to occur in macroevolution and even
in micro-evolution. The materials for evolution and the factors inducing and
361Microevolution and Macroevolution
directing it are also believed to be the same at all levels and to differ in mega-
evolution only in combination and in intensity. (Simpson 1944, 124)
In a later book, The Major Features of Evolution (1953), Simpson rein-
forced the idea that genetics of populations plays a direct role in the ex-
planation of the phenomenological patterns of evolution of higher taxa
by means of natural selection as the main mechanism. As we can see, the
core position of natural selection in Simpson’s theoretical framework is
clearly noticeable. As Beatty points out, the only “law” about the course
of evolution is the fact that it is “generally adaptive” (Beatty 2008).
These considerations show that Simpson shared the idea of the pre-
eminence of mev with the other authors of the biological synthesis. How-
ever, his role in the debate was particularly signiﬁcant because he “in-
serted” paleontology into the synthesis. With respect to the importance
of this move, it is worth recalling his own words about the integration
of paleontology and genetics, which “may be particularly surprising and
possibly hazardous” (Simpson 1944, xv). The insertion of paleontology,
however, did not have the effect on the relationship between mev and
Mev that one might expect. In fact, according to Simpson, paleontology
is autonomous only with respect to phenomenological issues, but not
about macroevolutionary processes. In other words, the role of paleon-
tology is restricted to the presentation and description of fossil records,
but it cannot propose speciﬁc processes to explain fossil patterns. It is
precisely for this reason that Eldredge and Tattersall (1982) “accused”
Simpson of being the scientist responsible for the “silence” of biology
about macroevolutionary mechanisms.
In general, Ernst Mayr conceived Mev as the origin of higher catego-
ries and the domain of the development of new organic systems. In other
words, Mev was understood as a process that encompasses all the evolu-
tionary processes that last for long periods of time and that involve enti-
ties belonging to higher levels. However, Mayr stated that,
All the processes and phenomena of macroevolution and the origin of the higher
categories can be traced back to intraspeciﬁc variation, even though the ﬁrst
steps of such processes are usually very minute. (Mayr 1942, 298)
Therefore, the study of intraspeciﬁc variations was the central goal of
Mayr’s analyses (Mayr 1996). Genetics and microevolutionary factors
should explain macroevolutionary phenomena.
With respect to the disciplinary role of paleontology, two arguments
underlying Mayr’s position need to be stressed. On the one hand, he
denied the capacity of paleontology to generate theories that can ex-
362 Guillermo FolGuera and olimpia lombardi
plain its own phenomena. In addition, he questioned the status of fossil
records by considering them not as inappropriate, but as insufﬁcient
(Mayr 1982). On the other hand with respect to the processes leading to
species and higher level entities, Mayr proposed mechanisms based on
the dynamics of populations. This clearly implies that, for him, Mev owes
its features to mev.
The phenomena of macroevolution cannot be understood unless they are
traced back to populations that are incipient species, and to neospecies. Major
macroevolutionary processes are initiated during peripatric speciation. (Mayr
In summary, Mayr’s stance about the relationship between mev and
Mev admits the possibility of reducing macroevolutionary phenomena
to microevolutionary mechanisms, and it implies the denial of the au-
tonomy of paleontology. In fact, these ideas should be contextualized in
the general notion of “population thinking,” the way chosen by Mayr to
discredit essentialist styles of thought within biology (Sober 1980). Al-
though the point is not the main purpose of this work, it is interesting to
identify the many causes that may have inﬂuenced Mayr in this respect.
Beatty (1994) suggests that the distinction between “essentialism” and
“population thinking” might have been important in his view of evolu-
tionary biology, as well as “a means of legitimizing philosophy of biology
as a special area of inquiry” (Beatty 1994, 353).
This brief summary clearly shows that in spite of the differences
among their general positions, the main representatives of the traditional
biological synthesis agree in the assumption of an asymmetric relation-
ship between mev and Mev. The mechanisms of evolution are supposedly
conﬁned to the microevolutionary levels and, as a consequence, the phe-
nomena of macroevolution have to be reductively explained by those
mechanisms. This position began to be challenged in the decade of the
1970s with the advent of the criticisms to the traditional synthesis.
The reconﬁguration of the relationship since the seventies
The relationship between mev and Mev has been frequently revised
since the 1970s. One of the most discussed topics has been the rate of
the evolutionary change, in particular, whether the rate is constant or
not. This was an issue explicitly addressed by the theory of punctuated
equilibrium, proposed by Niles Eldredge and Stephen Jay Gould (1972).
In a simple but clear characterization, the theory states, “species are
363Microevolution and Macroevolution
morphologically static throughout most of their history and have
distinct and rapid births and deaths” (Lieberman and Vrba 1995, 394).
This hypothesis was elaborated for the purpose of giving an account
of the interspeciﬁc patterns coming from a differential distribution of
phenotypic evolution among lineages (Gould and Eldredge 1977; Vrba
1984). In fact, phenomenological patterns show a “relative lack of
accumulation of phenotypic change throughout the known duration of
a species once it appears in the fossil record” (Eldredge 1992, 146).
The debate opened up by the theory of punctuated equilibrium also
involved the comparison between genetic patterns and fossil phenom-
enological patterns, in the line of Simpson’s words about the topic in
Tempo and Mode in Evolution (Shubin and Marshall 2000). The debate
naturally led to a critical analysis of the possibility that microevolution-
ary mechanisms explain macroevolutionary phenomena. In fact, ac-
cording to the theorists of the punctuated equilibrium, the reason why
abrupt changes in fossil patterns were ignored by the synthesis was the
assumption that fossil records could be accounted for by gradual genetic
variations in populations.
Because the population-dynamic formalisms operated on the assumption
of continuous and incremental genetic variation, all nongradualist forms of
evolutionary change were excluded. (Pigliucci and Müller 2010, 13)
In turn, as one might expect, the assumptions about the relationship
between evolutionary levels were inextricably linked with the already
intensively discussed issue about the comparative status of the different
disciplines belonging to the synthesis. In this sense, it is not surprising
that two of the most active representatives of the 1970 reaction, Eldredge
and Gould, are both well-known paleontologists.
That debate was just the beginning of a deep revision of the relation-
ship between mev and Mev. In this respect it is possible to recognize two
faces in the positions sustained by the new theorists, “negative” argu-
ments (criticisms to the theses of the biological synthesis) and “positive”
proposals (theories alternative to those theses). Both faces can be identi-
ﬁed in the same quotation from Gould.
If every evolutionary principle can be seen in a Drosophila [sic] bottle or in the
small and immediate adjustment of local populations on the Biston betularia
[sic] model, then paleontology may have nothing to offer biology beyond
exciting documentation. But if evolution works on a hierarchy of levels (as it
does), and if emerging theories of macroevolution have an independent status
within evolutionary theory (as they do), then paleontology may become an equal
364 Guillermo FolGuera and olimpia lombardi
partner among the evolutionary disciplines. (Gould 1980a, 98)
The acknowledgment of the presence of these two argumentative
positions is relevant to the purpose of the present paper. Certainly, the
negative arguments gained, at least, a partial success in the biology aca-
demic community. The difﬁculties of microevolutionary mechanisms
in explaining macroevolutionary patterns were in general admitted by
evolutionary biologists. But the agreement about the limitations of mi-
croevolution opened up a new question: which are the macroevolution-
ary processes that could explain fossil records? This positive search for
macroevolutionary mechanisms found obstacles much more serious
than those derived from the negative arguments. This problem was an-
ticipated by some researchers in the 1970s.
Paleontologists have supplied most of the direct observations of major phyletic
evolution in plants and animals, but they have been severely limited in their
efforts to clarify the associated evolutionary mechanisms because of the nature
of the fossil record. (Bock 1970, 704)
Among the several requirements to which the search for evolutionary
processes was subject throughout the twentieth century, an important
one was methodological. According to some authors, certain disciplines
cannot contribute to the understanding of evolutionary mechanisms be-
cause they deal with “higher levels of structural organization inacces-
sible to laboratory genetic approaches” (Love 2006, 319; see also Ayala
1982; Futuyma 1998; Lande 1976). It is quite clear that the requirement
of being accessible to laboratory experiments is only fulﬁlled by disci-
plines like population genetics, but not by paleontology.
Nevertheless, in spite of the difﬁculties, the critics of the biological
synthesis persisted in the search for alternative evolutionary mechanisms
appropriate for the levels of macroevolution. The main proposal in this
direction was the mechanism of selection.
[S]election is the interaction between heritable, varying, emergent characters of
individuals and the environment that causes differences in birth and/or death
rates of those individuals. (Lieberman and Vrba 1995, 394)
Selection was, then, introduced as a general mechanism, of which
natural selection of populations and of species are particular cases.
The positive proposals of the 1970s did not achieve wide acceptance
in the academic community due to diverse reasons, whose analysis is
beyond the purposes of the present paper. Although in the mid-1980s
some aspects of the new theoretical perspective were (at least partial-
365Microevolution and Macroevolution
ly) accepted, like certain theses of the punctuated equilibrium theory
(Gould and Eldredge 1986), problems subsisted. Indeed, Gould admit-
ted some difﬁculties regarding the adoption of hierarchical perspectives
within biology, in particular those derived from taking the possibility of
multiple units of selection not seriously enough.
Although arguments for a multiplicity of units of selection have been advanced
and widely discussed, evolutionists have generally held fast to the overwhelming
predominance, if not exclusivity, of organisms as the object sorted by selection.
(Gould 1982, 384)
The problems persisted during the following years. However, at the
beginning of the present century, the idea of an extended synthesis came
back. In the following sections we will analyze the general features of
“Altenberg 16” and the hierarchies in the context of the extension of
the biological synthesis
Hierarchies in the context of the extension of the synthesis
The need of extending the biological synthesis was put forward from
different perspectives during the following years. In 2008, fourteen bi-
ologists and two philosophers (known as “Altenberg 16”) introduced a
formal and explicit proposal of an extended synthesis. The members of
this group collaborated in the writing of a very motivating book entitled
Evolutio: The Extended Synthesis, edited by Massimo Pigliucci and Gerd
Müller (2010), where the current situation of the biological synthesis is
thoroughly analyzed. In that work, at least three aspects of the biologi-
cal synthesis are revised: ﬁrst, the predominance of the focus on gradual
patterns in paleontological records; second, the exclusive attention in
natural selection as the main evolutionary mechanism; and third, “gene-
centrism,” that is, “[t]he focus on the gene as the sole agent of variation
and unit of inheritance, and the dogmatic insistence on this stance by the
popularizers of the Synthesis” (Pigliucci and Müller 2010, 14).
It is very interesting to compare this position about the relationship
between mev and Mev with the criticisms raised in the decades of the
1970s and the 1980s. Both perspectives stress the need of a hierarchical
structure to account for evolution.
366 Guillermo FolGuera and olimpia lombardi
Documentation and analysis of macroevolutionary patterns in living and fossil
organisms amply demonstrate the need to more fully incorporate scale and
hierarchy into the Evolutionary Synthesis. (Jablonski 2010, 349)
This means that the Altenberg 16 favors the incorporation of differ-
ent levels in the account of evolutionary processes. In a way similar to
the previous proposal, the Altenberg 16 accepts a multilevel selection
theory, recognizing its high “potential for empirical and theoretical ad-
vances” (Jablonski 2010, 344) and claiming that it is “essential to un-
derstanding long-term evolutionary processes” (Jablonski 2010, 350). In
this context, the question about how the relationship between mev and
Mev is characterized by this proposal is particularly relevant in the light
of our main objective.
Multilevel processes, or at least a failure of simple extrapolation from short-
terms, local processes, are often evident in the dynamics of evolutionary trends,
which can unfold via differential origination (…), differential extinction (…), or
directional speciation (…). Although clades may evolve in directions consistent
with patterns of intraspeciﬁc variation (…) simple extrapolation from short-
term processes often breaks down –as might be expected, given the scarcity of
directional species-level evolution over geological timescales. (Jablonski 2010,
In other words, microevolutionary and macroevolutionary processes
may evolve in different “directions” depending on the case under consid-
eration. Even in the case of the selection on organisms, which is strongly
correlated with clade dynamics, multilevel analysis is desirable because
“the combined forces will be more effective in driving large-scale change
than either would be independently” (Jablonski 2010, 344).
In summary, there are telling points of contact between the proposals of
the Altenberg 16 and the negative arguments developed by the 1970
critics with regard to the conception of evolutionary processes. Both
perspectives point to the limits of natural selection and stress the need
of searching for alternatives to the central role traditionally assigned to
gene. In addition, the new theoretical framework does not introduce sig-
niﬁcant “novelties” when compared with the positive proposals of those
1970 works. In this respect, one of the scientists of the Altenberg 16
asserts that “the revival of the [multilevel selection] theory shows that it
continues to be an important extension in contemporary research” (Wil-
son 2010, 88). It seems to be clear that the viewpoint of the Altenberg
16 still stands very close to the selective scenario, but in a hierarchical
367Microevolution and Macroevolution
Structure and interdisciplinary relations
At this point, it is pertinent to analyze whether the recently proposed
extension only involves the incorporation of “new” areas of knowledge
(genomics, Evo-Devo and Mev), or whether it also modiﬁes the relation-
ships among disciplines. With respect to this question, one of the philos-
ophers of the Altenberg 16, Alan C. Love, contributes to the 2010 book
with a relevant chapter, suggestively entitled “Rethinking the structure
of evolutionary theory.” Love emphasizes the importance of distinguish-
ing between structure and content in the biological synthesis. In his own
words, content includes “empirical ﬁndings, dynamical models, and key
concepts, among other items” (Love 2010, 435), whereas structure re-
fers to “how the content is organized” (Love 2010, 405). As we have
seen, since the 1940s to the 1960s the relationships between disciplines
were considered as clearly asymmetric, as a consequence of the extrapo-
lation of the microevolutionary processes to the Mev domain. Therefore,
the proposal of new evolutionary mechanisms to explain the higher lev-
els of the structural organization of the phenomenon of evolution is an
unavoidable step toward revoking that asymmetry. This means that the
new structure of evolution will immediately be reﬂected in the structure
of biology itself, which will incorporate interdisciplinary links different
than those implicitly or explicitly accepted in the traditional synthesis.
The analysis of the structure of the extended synthesis clearly shows
its multidisciplinary character. The multidisciplinary approach of the
new synthesis should lead not to a mere juxtaposition of disciplines,
but to an integration that will give rise to novel results: “[e]volutionary
theory needs to be a synthesis of disciplinary approaches in order to
produce an integrated or cohesive body of scientiﬁc knowledge” (Love
2010, 421-422). This point establishes a direct link between the problem
of the role of disciplines in evolutionary biology with the own structure
of the biological synthesis. “An erotetic structure for evolutionary theory
in terms of an organization of problem agendas with diverse disciplinary
contributors provides a standpoint for prospects and possibilities of an
extended synthesis” (Love 2010, 433). In the case of the proposal of the
Altenberg 16, one of the most criticized topics is the “gene-centrism” of
the biological synthesis. In this sense, Gregory A. Wray claims:
Information from molecular biology, developmental biology, and, most recently,
genomics are prompting substantial changes to the gene centered view that
emerged during and shortly after the Modern Synthesis. (Wray 2010, 110)
368 Guillermo FolGuera and olimpia lombardi
From a similar standpoint, Pigliucci asserts that in the extended syn-
thesis, “genes could come to be seen as “followers” rather than leaders
in the evolutionary process, a change that may have little impact on,
say, research in molecular genetics, but that would represent a major
conceptual shift in evolutionary theory” (Pigliucci 2010, 370). But, what
are the changes that are producing the extension of the structure of the
Microevolution, macroevolution and pluralism
Let us recall the positive strategy adopted by the 1970 reaction, with
its postulation of selection as a general multi-level selective mechanism.
It is certainly true that such a mechanism cannot be uncritically identi-
ﬁed with natural selection and that it does not amount to a mere rep-
etition of microevolutionary mechanisms in the context of Mev (Gould
1980b). In fact, Gould and other scientists made sustained efforts to
clarify the differences between selection and natural selection. Whereas
selection is understood as the “differential birth and death among vary-
ing organisms within a population” (Vrba and Gould 1986, 217), natural
selection is only one of its possible causes. This argumentative strategy
shows that, according to the 1970 reaction, not all cases of selection
are due to natural selection (Lieberman and Vrba 1995). However, this
conclusion does not cancel the fact that, in this new view, the processes
of mev and Mev still have an analogous structure (Folguera and Rendón
2010). Sometimes this analogy is even explicitly admitted: “selection op-
erates, in a manner analogous to Darwinian natural selection, at several
levels in addition to genes and organisms” (Lieberman and Vrba 1995,
394). This means that, in a certain sense, mev is analogically expanded to
other domains of evolution, in particular, to Mev.
But complexities arise when we expand the concept of selection hierarchically,
and more precision is required in a statement of selection that applies equally to
sorting among genomic constituents and among species. (Vrba and Gould 1986,
One of the main purposes of the 1970 critics of the biological syn-
thesis was, of course, to modify the traditional relationship between mev
and Mev (see, for example, Lieberman and Vrba 1995; Vrba and Gould
1986). However, their analogical strategy still implies the priority of mev
over Mev. Such priority, although non-reductive, derives from the fact
that mev is taken as the model for evolution at all levels. In other words,
369Microevolution and Macroevolution
there is no novelty in the macroevolutionary levels to the extent that
their mechanisms are analogically extrapolated from the levels of mi-
croevolution. As a consequence, despite their explicit purpose, those
theoretical positions that emerged in the 1970s reproduce, although in a
different way than in the case of the traditional synthesis, the asymmetry
between mev and Mev.
In turn, the authors of the Altenberg 16 also recognize the need of
ﬁnding macroevolutionary mechanisms: “Here, too, evolutionary mech-
anisms are poorly known” (Jablonski 2010, 341). As we have seen, in
general they agree with the positive strategy adopted by the 1970 reac-
tion. In fact, they support the idea of selective processes at different
levels. Nevertheless, they do not revise the analogical extrapolation of
mechanisms from mev to Mev. This means that both the hierarchical
evolutionary domain and the disciplinary domain continue to display
an asymmetric structure (Folguera and Rendón 2010). Summing up,
in spite of the words of Love cited above that referred to the revision
of “the gene-centered view,” the Altenberg 16 could not succeed in in-
troducing a substantial modiﬁcation in the relationships between evo-
lutionary levels and between biological disciplines with respect to the
However, this extension of the biological synthesis involves other im-
portant complexities that lead us to a more detailed analysis. Undoubt-
edly, one of the areas that have implied deep re-examination and changes
within biological synthesis is Evo-Devo. In this area, different concepts
and theories were elaborated (and recovered), which have converged
toward the gradual unfolding of a new scenario in the evolutionary biol-
ogy. For instance, a concept like epigenesis is a clue in the attempt to
turn genes into mere “followers” rather than leaders in the evolutionary
process. However, the extent of the involved changes is not clear yet.
In the example of epigenesis, it is an open question concerning the em-
pirical and theoretical scope associated to phenomena such as genetic
assimilation, environmental inﬂuences, or transgenerational epigenetic
inheritance; that is, “the inheritance of phenotypic variation in cells and
organisms that do not depend on variations in DNA sequence” (Jablon-
ka and Lamb 2010, 143). In the context of this conceptual framework,
the main challenge of any extended synthesis involves not only a review
of the content of the evolution, but also the need of rethinking the struc-
ture of evolution, with its levels and the links among them. With respect
to this problem, although Love admits that the positive program of ﬁnd-
ing alternatives to the synthesis is not an easy task, he suggests a kind of
pluralism as a promising perspective.
370 Guillermo FolGuera and olimpia lombardi
If evolutionary theory is composed of multiple problem agendas that require
contributions from diverse disciplinary perspectives, there is no “fundamental”
viewpoint or level to which we can reduce our picture of the evolutionary
process. […] This plurality of biological disciplines, offering complementary
and competing contributions to multidisciplinary explanations of phenomena
related to problem agendas, is suitable matched with a pluralism about structure
in evolutionary theory […]. (Love 2010, 433)
A pluralism of this kind rejects any assumption of priority of certain
levels on the others. In turn, this requires a reassessment of the role that
each discipline plays in the context of the biological synthesis. Certainly,
these revisions are not exempt from new problems, some of which will
be discussed in the next and last section.
The roles of the disciplines and the problem of integration
The previous sections suggest the need of facing the following new
question regarding this pluralistic proposal of extension: how can the
integration among the different areas of biology be performed? Regard-
ing this problem, William Bechtel notices that, in the history of biology,
The most common model for accomplishing uniﬁcation has been the logical
positivists’ model of theory reduction, according to which theories of one
discipline are derived from theories of other disciplines (together with necessary
bridge laws and boundary conditions). (Bechtel 1993, 277)
Certainly, this strategy of integration by reduction has been very com-
mon in biological sciences. However, this strategy offered much less re-
sults than expected.
Perhaps the strongest vision of unity appeared in the theory-reduction model
of the logical empiricists. This model was attractive because it suggested that
logic might provide a powerful way to unite the results all scientiﬁc inquiries by
showing higher-level theories to be derivable from lower-level ones. Not only
were serious objections raised against this model, but as we have seen, much of
the unity that appears to result is illusory. (Bechtel and Hamilton 2007, 40)
In biology, the cases of reduction (sensu strictu) have not been fre-
quent (Burian 1993). In the particular case of the relationship between
evolutionary domains, the phenomena at the macroevolutionary levels
could never be strictly explained or derived from the mechanisms and
processes at the microevolutionary levels. Therefore, on what basis did
traditional synthesis perform the desired integration? The integration
371Microevolution and Macroevolution
sustained by that theoretical framework was based, not on deductive
reduction, but on the assignment of different roles to the disciplines be-
longing to the synthesis. As we have seen, according to that view the
explanatory role in biology was reserved exclusively for population ge-
netics, whereas paleontology was conceived as a merely descriptive dis-
cipline. In addition, the assignment of different roles can be detected in
other proposed mechanisms; see, for instance, the notion of changes in
the genetic regulatory program for the development of the body plan
(Davidson et al. 2002; Davidson and Erwin 2006).
Certainly, the strategy of the architects of the biological synthesis was
efﬁcient for attaining the desired result of integration. However, this
strategy also produced a highly negative effect on the role of the “sec-
The proliferation and heterogeneity of life science disciplines and methodologies
following the advent of molecular biology had led to a centrifugal force within,
making it difﬁcult to recover a single big-picture or “grand uniﬁed theory”.
(Love 2010, 433)
This “centrifugal force” did have a strong disruptive effect in biology.
This means that there is a considerable tension between the need of in-
tegration and the negative effect of the traditional integrative strategy on
certain disciplines and their domains of research. The acknowledgment
of such a tension, as well as the attempt to overcome it, represents the
most important challenge that an extended synthesis must face in the
The difﬁculties of the traditional approach to integration open up the
possibility of exploring new “bridges between theories without either
one being reduced to the other” (Bechtel and Hamilton 2007, 22). One
of these new proposals of integration is based on the interesting notion of
“ﬁeld,” which Darden and Maull characterize in terms of
a central problem, a domain consisting of items taken to be facts related to
that problem, general explanatory facts and goals providing expectations as to
how the problem is to be solved, techniques and methods, and sometimes, but
not always, concepts, laws and theories which are related to the problem and
which attempt to realize the explanatory goals. (Darden and Maull 1977 cited in
Bechtel and Hamilton 2007, 22)
In this way,
Interﬁeld theories sometimes serve simply to bridge existing disciplines, allowing
practitioners in each discipline to utilize techniques developed and knowledge
procured in the other. In the most interesting cases, however, constructing a
372 Guillermo FolGuera and olimpia lombardi
bridge between ﬁelds or disciplines results in the construction of a new discipline.
(Bechtel and Hamilton 2007, 23)
What should the integration strategy be in the case of evolutionary
synthesis? As we have seen, we have detected different kinds of relation-
ships among evolutionary areas. In each proposal, we found a different
sort of dependence of Mev on mev. In this context, it might be suggested
that Evo-Devo could play a relevant role in the desired extension of bio-
logical synthesis, by building up a meaningful bridge between the two
areas of evolution: mev and Mev. However, the ability of Evo-Devo to play
this role is still a very controversial matter. In our opinion, the goal does
not consist merely in the generation of new disciplines corresponding to
the relationships between different ﬁelds, in particular, between mev and
Mev. In any case, we consider that it is also necessary to redeﬁne the roles
of the different disciplines pertaining to the biological synthesis.
This work was supported by grants of the Universidad de Buenos Ai-
res and the CONICET of Argentina. The authors wish to thank to two
anonymous reviewers for comments on an earlier version of this paper.
In addition, GF acknowledges the CONICET for his post-doctoral fel-
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