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scientia
Peer Reviewed National Science Journal
Volume 12. No.1 Jan-Dec.2016 ISSN: 0976-8289
Published by:
MERCY COLLEGE
PALAKKAD 678006, KERALA, INDIA
Jan - Dec 2016
scientia Volume 12. No. 1. ISSN: 0976-8289
Scientia (Annual)
Volume 12. No.1 Jan-Dec.2016 ISSN: 0976-8289
949494
Scientia ISSN: 0976-8289
Vol. 12, No.1, Jan.-Dec., 2016, pp. 94-100
A Study on the Expression of Some Selected
Human Morphogenetic Traits in Thrissur District
Usha A U,* Sidjo Sunny, Stejin P. George, Alisha K.S., Anjana C.P., Anju M.,
Desny Davis, Nimmy Johnson, Reshma Sunny, Sangeetha A.S., Shini Shaji, Sneha A.A.
PG and Research Department of Zoology, St. Thomas College (Autonomous),
Thrissur, Kerala – 680001, India
Abstract
Morphogenetic characters are physical characters of an individual and the pattern of inheritance of
these traits is autosomal dominant as well as autosomal recessive. The present study was conducted
to screen random population for ten dierent morphogenetic traits i.e. ear lobe attachment, dimples,
crossing of thumb, crossing of arms, widow’s peak, tongue rolling, chin cleft, arched foot, Hitchhik-
er’s thumb, handedness to nd out the frequency of expression in individuals, which is dominant or
recessive. A total of 1130 individuals were subjected to this study. The prevalence of these morpho-
genetic traits was observed as; dominant traits such as free ear lobe (65.5%), able to tongue rolling
(53%), arched foot (67%), straight thumb (63.6%), right handedness (97.6%), etc. are expressed more
frequently in the population. But, same time the recessive characters like absence of dimples (79.5%),
crossing of thumb right over left (56.9%), absence of widow’s peak (70%), crossing of arm left over
right (53.8%), smooth chin (76.2%), etc,. are expressed more frequently in the population. We analysed
whether a trait is dominant or recessive. The survey result shows a variation of this argument, it shows
that some typical dominant character was not expressed but the expression of recessive character was
prevalent as in the case of widow’s peak (absent), smooth chin, crossing of thumb; right over left, Hitch-
hiker’s thumb (straight), absence of dimple, etc, all of which are recessive traits.
Keywords: Morphogenetic traits, Human genetics. Hitchhiker’s Thumb. Widow’s peak. Dimples
Introduction
Genetic variability is the characteristics
of living things, especially in human beings.
They show varieties of morphogenetic char-
acters among one population itself 1. Morpho-
genetic characters are physical characters of
an individual and the pattern of inheritance
of these traits is autosomal dominant as
well as autosomal recessive 2. Human pop-
ulation provides an exclusive opportunity to
study the morphogenetic variation among
the endogamous populations living in dif-
ferent geographical and ecological circum-
stances 3. The presence of genetic variation
in man is controlled by many factors includ-
ing assortment, migration, and genetic
drift4. Human genetics deals with the study
of inheritance as it occurs in human beings.
The advancement and research in the eld
of human genetics have made great socio
economic contribution for human welfare.
The principle of genetics concern largely
with an explanation of the dierences exist-
ing among individual 5. It helps in analys-
ing the potentialities of individuals already
leaving as well assign predicting the trait of
future ospring from a given mating5.
In this study, we discuss some human
traits which are more prevalent in our com-
munity. When one learns about dominant
and recessive alleles, there is often a mis-
conception that dominant alleles are the
most common and they will tend to crowd
out the recessive alleles in course of time.
The frequency of a character in a population
is related to whether its phenotypic eect
is favourable or unfavourable. It was only a
∗
Corresponding Author, Email: ushaunni77@gmail.com
Usha: Expression of Selected Morphogenetic Traits
95
preliminary attempt to study the expression
of some traits in a population of Thrissur
.The main objectives of this study were to
assess the frequently expressed morphoge-
netic traits among the population of selected
areas of Thrissur district and also to check
which trait is more dominantly or reces-
sively expressed in the population and to
make a comparison of male and female per-
centage dierence in the expression of the
traits.
Materials and Methods
Study area
i) The survey was conducted in randomly
selected areas of Thrissur district (Fig. 1).
ii) Data collection and tabulation
The Survey method was chosen for data
collection. We had prepared a data collection
table, which include the individual’s name,
sex, age, and trait, whether it as a dominant
or recessive trait based on the phenotypic
expression in that individual. We preferred
the subjects within the age range of 10 to
70 years. A total of 1130 individuals were
observed for 10 dierent morphogenetic
traits such as Ear lobe, Dimples, Crossing
of thumb, Crossing of arms, Widow’s peak,
Tongue rolling, Chin cleft, Arched foot,
Curved thumb, Handedness, from the ran-
dom population. Out of 1130 subjects, 565
were females and 565 were males.
Following are the description of selected
morphogenetic traits, we have observed for
dominance and recessiveness that can be
easily observed in people around us.
1. Earlobe attachment
If earlobes hang free, they are detached.
If they attach directly to the side of the head,
they have attached earlobes 6. This is due to
a gene that is dominant for unattached ear
lobes and recessive in the case of attached
ear lobes. If more people have attached ear-
lobes then that is the most prevalent 7.
2. Dimples
Dimples are round indentations in the
cheeks when smiling, not lines or clefts.
They are reportedly due to a single gene
with dimples dominant and a lack of dim-
ples recessive 8.
Fig.1 Study area (source: http://www.thehindu.com/news/national/kerala/)
SCIENTIA Jan-Dec. 2016
96
3. Crossing of Thumbs
In a relaxed interlocking of ngers, left
thumb over right results from having one
or two copies of the dominant version of the
gene 9. People with two recessive place right
thumb over left.
4. Crossing of arms
When the arms are folded across the
chest, having the left arm positioned on top
is the dominant characteristic whereas hav-
ing the right arm positioned on the top is
the recessive characteristic 9.
5. Widow’s Peak
A widow’s peak or the mid-digital the
hairline is due to expression of the gene for
hairline. This gene has two alleles, one for
widow’s peak and one for the straight hair-
line. The widow’s peak allele is dominant
and the straight allele is recessive 10.
6. Rolling of Tongue.
Tongue rolling is the ability to roll the
lateral edges of the tongue upwards into a
tube. If you can roll the lateral edges of your
tongue together, then this means you have
inherited a dominant trait. Those who are
unable to do so are expressing inheritance
of recessive gene for tongue rolling 11.
7.C hin
People can have a cleft chin or smooth
chin. Cleft chin or dimple chin refers to a
dimple on the chin. It is a y- shaped ssure
on the chin with an underlying bony pecu-
liarity. This is an inherited trait in humans,
where the dominant gene causes the cleft
chin, while the recessive genotype presents
without a cleft 12.
8. Foot
In humans, the allele for having a foot
with normal arches is dominant. The allele
for at foot is recessive. People with arched
foot have a distinct curve along the inside of
the foot with a band slightly less than half
the width of the foot connecting the heel &
toe. Flat foot refers to a change in foot shape
in which the foot does not have a normal
arch when standing.
9. Hitchhiker’s Thumb
Thumb can be straight or curved (Hitch-
hiker’s thumb). Straight thumbs can be seen
as nearly a straight line and may contain a
slight arch when viewed from the side. A
Curved thumb is dominant over a straight
thumb.
10.Handedness
The gene for right-handedness is dom-
inant and the gene for left hand is reces-
sive. Thus, majority of the people have
inherited the dominant gene resulting in
right-handedness.
iii) Statistical analysis
After data collection a primary consoli-
dation of data was done. Appropriate graph-
ical representation and statistical analysis
(Student’s paired T test (two tailed), Spear-
man’s correlation-signicance level 5%) was
also done.
Result and Discussion
A total of 1130 individual were observed
for morphogenetic traits - Ear lobe, Dim-
ples, Crossing of thumb, crossing of arms,
Widow’s peak, Tongue rolling, Chin cleft,
arched foot, Hitchhiker’s thumb and Hand-
edness from the random population.
The results show the clear cut view of
the expression of traits in each individual in
the population. A graph (Fig.2) were plotted
for dominant and recessive traits classied
based on their expression. Out of 1130 indi-
viduals, 599 individuals were capable to
roll their tongue and others were not able
of rolling their tongue. About 741 individu-
als of the population have free ear lobes and
44.9% has attached ear lobes. The survey
showed that 231 of the population had facial
dimples and 899 subjects are without this
trait. About 339 subjects are having widow’s
peak in their head and 791 individuals are
not having this trait. About 719 individuals
have curved thumb and 411 subjects have
straight thumb. Out of 1130 individuals,
758 individuals are having arched foot and
372 are having at foot.
The results showed that 268 individuals
are having cleft chin and 862 individuals are
Usha: Expression of Selected Morphogenetic Traits
97
having smooth chin. The pattern of crossing
of arms and thumbs were also surveyed,
here results showed that 644 individuals
are cross their thumb in a pattern of right
over left, and others are cross their thumb
left over right.521 individuals cross their
arms right over left and 609 individuals
cross their arms left over right. Right Hand-
edness were showed as one of the most dom-
inant trait in the survey, this shows a clear
dierentiation between dominant and reces-
sive characters in handedness trait, only 26
individuals are have left handedness.
Table 1: The percentage wise difference of dominant and recessive traits between male and female
Tra i t
Number
of male
dominant
Number
of male
recessive
% of
dominant
males
% of
recessive
males
Number
of female
dominant
Number
of female
recessive
% of
dominant
female
% of
recessive
female
Ear lobe 351 214 62.12 37.87 390 175 69.02 30.97
Dimples 116 449 20.53 79.46 115 450 20.35 79.64
Crossing of
thumb 331 234 58.58 41.41 323 242 57.16 42.83
Crossing of
arms 289 276 51.15 48.84 232 333 41.06 58.93
Widow’s peak 182 383 32.21 67.78 157 408 27.78 72.21
Tongue rolling 339 226 60 40 260 305 46.01 53.98
Chin 153 412 27.07 72.92 115 450 20.35 79.64
Foot 404 161 71.50 28.49 354 211 62.65 37.34
Thumb 365 200 64.60 35.39 354 211 62.65 37.34
Handedness 549 16 97.16 2.83 555 10 98.23 1.76
Fig. 2. Difference between dominance and recessiveness of the trait among total subjects.
SCIENTIA Jan-Dec. 2016
98
Table.1 shows the percentage wise dif-
ference between male and female subjects.
About at 46% female and 60% males were
able to roll their tongue. About 53.8% of the
population cross their arms right over left.
Fifty nine percent of female and 48.8% male
had crossed their arms right over left. Fifty
seven percentage of the sampled individuals
cross their thumb right over left; 58.8% male
and 57.1% females sampled showed this
trait. The survey showed that 20.4% of the
population had facial dimples. Only 20.3%
of females and 20.5% of males showed this
trait. About 23.7% subjects have chin cleft;
20.3% of females and 27% of male subjects
had this trait. About 30% of individuals pos-
sess widow’s peak. Gender wise, 27.7% of
females and 32.2% males had widow’s peak.
About 67% subjects have arched foot; 62.6%
of females and 71.5% of males had arched
foot. About 65.5% individuals have free ear
lobes. Free ear lobes were seen in 62.1%
males and 69% females. Posture of thumb
was curved in 63.6% individuals; 64.6%
males and 62.6% were females. Right Hand-
edness was one of the prominent distin-
guishable characters in this survey; it shows
about 97.6% of expression in individuals.
Right handedness was expressed in 97.1% of
males and 98.2%of females.
Fig. 2 shows that traits like ear lobe,
crossing of thumb, arched foot, Hitchhik-
er’s thumb, and handedness are expressed
as dominant in both males and females.
Whereas traits like dimples, widow’s peak
and cleft chin are expressed as recessive
in both male and females. Some traits like
crossing of arms and tongue rolling showed
dierence in the expression of alleles in both
sexes with more males showing the domi-
nant character and more females showing
the recessive character.
The study found that there was no
signicant dierence between the num-
ber of dominant and recessive characters
expressed either in male and females. There
was also no signicant gender dierence
in the expression of dominant or recessive
characters with most of the traits showing
the same pattern of expression in either sex.
i) Male dominant and recessive
There is no signicant dierence between
the expression of dominant and recessive
characters of selected traits in males [(t
Fig.3. Percentage difference between dominant and recessiveness in male and females
Usha: Expression of Selected Morphogenetic Traits
99
(observed value) = 0.620, t (critical value) =
2.262) two tailed paired t-test at 5% signif-
icance for N (traits) =10. The risk to reject
the null hypothesis H0 while it is true is
55.06%.
ii) Female dominant and recessive
There is no signicant dierence between
the expression of dominant and recessive
characters of selected traits in females [(t
(observed value) = 0.069, t (critical value) =
2.262) two tailed paired t-test at 5% signif-
icance for N (traits) =10. The risk to reject
the null hypothesis H0 while it is true is
94.69%.
iii) Male dominant and Female dominant
There is no signicant dierence in the
expression of selected dominant characters
in both males and females [(t (observed
value) = 2.046, t (critical value) = 2.262)
two tailed paired t-test at 5% signicance
for N (traits) =10. The risk to reject the null
hypothesis H0 while it is true is 7.10%.
iv) Male recessive and Female recessive
There is no signicant dierence in the
expression of selected recessive characters
in both males and females [(t (observed
value) = - 2.046, t (critical value) = 2.262)
two tailed paired t-test at 5% signicance
for N (traits) =10. The risk to reject the null
hypothesis H0 while it is true is 7.10%.
We analysed whether a trait is dominant
or recessive, and if the expression happens
based on dominance. The survey result
shows a variation of this argument; it shows
that some typical dominant characters were
not expressed but the expression of reces-
sive character was prevalent as in the case
of widow’s peak. Presence of widow’s peak is
a dominant character in population but, as
per our study the absence of widow’s peak
(regarded as a recessive character) was more
prominent in the population. The same was
in the case of cleft chin, crossing of thumb;
right over left, Hitchhiker’s thumb (curved),
absence of dimple, etc, all of which are reces-
sive traits. In one study conducted in Nige-
ria, on Morphogenetic traits combination
pattern amongst the population shows some
signicant results like morphogenetic com-
binations might be rare in that population13.
Study of the inheritance pattern of human
traits is one of the signicant methods for
analysing the genetic history of a population
14. It has an important role in the determi-
nation of the chance of occurrence of genetic
diseases in the family otherwise in the soci-
ety, pedigree analysis is one of the basic and
important methods of genetic analysis of
human families. It will study and trace their
ancestral inheritance patterns and reaches
at accurate understandings about the fam-
ily history 15.
We conclude from our study that unlike
the preconceived notion that dominant
alleles are always expressed more, the
expression of dominant and recessive char-
acters may vary and may depend on various
factors.
Acknowledgement
We express our heartfelt gratitude to
everyone who has given immense help and
support to complete this study. We are espe-
cially thankful to Dr. Francy K. Kakkssery,
Head, Department of Zoology for permitting
the study to be undertaken and issuing nec-
essary permission and Dr. Joyce Jose for
help in statistical analysis to complete this
study.
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scientia
Peer Reviewed National Science Journal
Volume 12. No.1 Jan-Dec.2016 ISSN: 0976-8289
Published by:
MERCY COLLEGE
PALAKKAD 678006, KERALA, INDIA
Jan - Dec 2016
scientia Volume 12. No. 1. ISSN: 0976-8289
Scientia (Annual)
Volume 12. No.1 Jan-Dec.2016 ISSN: 0976-8289
