Are Men Evolving Faster Than Women Biology Essay

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Is it possible for the so called "primitive man" to be evolving faster than "matured, well mannered woman" or is this just a myth created by a male individual. Scientific evidence has proven that the Y chromosome, which is only present in males, is the fastest changing part of the human Genome. Yet is this rapid evolving beneficial or is it just creating false hope for men. Can statistics such as "number of woman in government, Y chromosome mutations" enhance the counter argument that "Men are not evolving faster than woman". The fact that scientific evidence proves the Y chromosome to be evolving at a rapid rate establishes men are evolving faster than woman. Although that's true it does not mean men themselves are more evolved then woman.

Y chromosome is one of the two sex determining chromosomes in humans, the other obviously being the X. DNA consists of total of 2 percent of Y chromosomes which is made up of 58 million building blocks of DNA (base pairs). Normally a person has one pair of sex chromosomes in each cell. Males have one X and one Y chromosome compared to females whom have two X chromosomes. The Y chromosomes consist of 70 to 200 genes. As males only have the Y chromosome these genes on the Y chromosome are involved in male sex determination and devolvement. SRY (Sex-determining Region) gene determines sex. This gene is also responsible for the foetus developing into a male. Other genes on Y chromosome are important for male fertility. Large variety of genes are unique to Y chromosome although genes in areas known as pseudoautosomal region are present in both X and Y chromosome. This leads to men and woman each having two functional copies of these genes. Genes present in pseudoautosomal region are vital for normal development. Estimated Total of 20000 to 25000 genes in the human genome is of the Y chromosomes. (2)http://www.in-gender.com/cs/blogs/gender_selection_news/y-chromosome.jpghttp://users.rcn.com/jkimball.ma.ultranet/BiologyPages/Y/Ychromosome2.gif

Y chromosome

A pseudoautosomal region that is homologous to a region of the X chromosome. They are responsible for sex pairing and Y-specific part that encodes the sex determining gene. Pseudoautosomal region contains other genes but these are not sex linked. (4)

Evidence proving that the Y chromosome is evolving faster has been found by Whitehead Institute researchers. They have found considerable differences in the genetic sequences of the human and chimpanzee Y chromosomes. Whitehead Institute was the first to conduct a comprehensive interspecies comparison of the Y chromosome. It showed an indication that these chromosomes evolved more quickly than the respective genomes over 6 million years where they first emerged from common ancestor. It was found that the region that is evolving the fastest is the part that plays a role in sperm production. The rest of the Y chromosome is evolving more like the rest of the genome, slightly faster though. (2) The Y chromosomes of the two registered a difference of 30%. This is about a 2% more of a difference registered between other genes of the two species. Scientists have noticed that the Y chromosome keeps evolving constantly. The genes in the two species were so different that the human one has been recorded to have entirely new sections. Since the Y chromosome of the chimpanzee has not been completely studied leave doubt to which chromosome is evolving faster. (3)Image: X and Y chromosome

"A comparison of human X and Y chromosomes shows how small the Y chromosome is."

Research which should have taken two-years to complete took twice as long due to the evolutionary changes found. (1) Although all human and chimp chromosomes have been mapped only 2 have been examined in great detail, chromosome Y and 21. Even though there is still enough known to make the claim that the Y chromosome it the speediest evolver. (1)

The speedy rate at which the Y chromosome is evolving at might lead to mutations in Y chromosome. A large variety of conditions are related to changes in particular genes on the Y chromosome. Changes in structure and number of copies of a chromosome lead to problems arising. Problems such as Swyer Syndrome, Y chromosome infertility and 46,XX testicular disorder of sex development.

Swyer Syndrome is a condition where individual with one X chromosome and one Y chromosome in each cell. The pattern is normally found in males yet they will have female appearance. People affected by this disorder will have female genitalia and normal uterus and Fallopian tubes but no functional gonads (ovaries or testes). They will instead have undeveloped clumps of tissue known as streak glands. These streak gonads are likely to become cancerous therefore leading them to be surgically removed. This syndrome occurs in approximately 1 in 30,000 people. Children affected by this syndrome are normally raised as females. Genes related to swyer syndrome have been linked to mutations in the SRY gene, NR5A1 and DHH genes and changes affecting the NR0B1 gene have also been identified.(2)

Y chromosome infertility is a condition which affects the production of sperm. This either makes it extremely difficult or impossible for affected male to father his own child. This condition either prevents male body from producing sperm cells (azoospermia), smaller than usual number f sperm cells are produced (oligospermia) or abnormally shaped sperm cells are produced. (2)http://www.pittsburghcryobank.com/Images/male_factor_sperm.jpg

(5)

Abnormal Sperm

Normal Oval Form

Y chromosome infertility affects males of all ethnic groups. Approximately 1 in 2000 to 1 in 3000 males will acquire the disorder. Y chromosome infertility accounts for between 5 to 10 percent of case of azoospermia and serve oligospermia. Y chromosome infertility stems from deletions of genetic material in regions of Y chromosome called azoospermia factor (AZF), A, B or C. These genes are believed to provide instructions for the making of proteins which in turn is involved in sperm development. The functions of these specific proteins are still not well understood. Deletions in the AZF regions affect several genes. Its missing genetic material is the likely cause in the prevention of a number of proteins being developed for normal sperm cell development. In rare case Y chromosome infertility can be linked to changes in single gene called USP9Y. This gene is also involved in the making of proteins (ubiquitin-specific protease 9) by providing instructions. (3)

44 XX testicular disorder of sex development is when individual with X chromosomes in each cell this normally occurs in females yet the females will have a male appearance. This disorder occurs in approximately in 1 in 20000 individuals. Individuals with this disorder have male genitalia; generally there are abnormalities such as small testes and or urethra opening on underside of the penis. Affected children are raised as males. There are two forms of 44,XX testicular disorders, a SRY positive form (80%) and SRY negative form (20%). Positive form caused by abnormal exchange of genetic material between chromosomes (translocation). The translocation caused SRY gene to be misplaced almost always onto X chromosome. If fetus is conceived from the sperm cell which has an X chromosome bearing the SRY gene, it will develop into male even though is does not have Y chromosome. Negative form is when the individual suffering from 46,XX testicular disorder of sex development does not have SRY gene. This cause of disorder is unknown. They more than likely to have ambiguous genital than people with the SRY-positive form disorder. (4)

Table of genes on the Y chromosome and disorders related to those genes.

"Disease genes" are found on chromosome Y

Copied table from; http://www.genecards.org/cgi-in/listdiseasecards.pltype=chrom&search=Y

GeneCard

Gene Name

Locus

Disorders

AMELY

amelogenin, Y-linked 

Yp11

mutations

CDY1

chromodomain protein, Y-linked, 1 

Y

Y Chromosome Infertility

DAZ1

deleted in azoospermia 1 

Y Chromosome Infertility

DAZ2

deleted in azoospermia 2 

Yq11.2

mutations

DDX3Y

DEAD (Asp-Glu-Ala-Asp) box polypeptide 3, Y-linked 

Yq11

Y Chromosome Infertility

DFNY1

deafness, Y-linked 1 

Y

Deafness, Y-linked 1

HEY

unknown 

Yq

Hairy ears, Y-linked

HSFY1

heat shock transcription factor, Y-linked 1 

Y Chromosome Infertility

NLGN4Y

neuroligin 4, Y-linked 

Yq11.2

mutations

RBMY1A1

RNA binding motif protein, Y-linked, family 1, member A1 

Yq11

Y Chromosome Infertility

RPY

Retinitis pigmentosa, Y-linked 

Y

Retinitis pigmentosa, Y-linked

SRY

sex determining region Y 

Yp11.3

Gonadal dysgenesis, XY female type [MIM:306100]

Hermaphroditism, true [MIM:235600]

TDF

tumor differentiation factor 

Yp11.3

Gonadal dysgenesis, XY female type [MIM:306100]

Hermaphroditism, true [MIM:235600]

USP9Y

ubiquitin specific peptidase 9, Y-linked 

Yq11.2

Azoospermia [MIM:415000]

YBX2

Y box binding protein 2 

mutations

YEATS4

YEATS domain containing 4 

12q13-q15

Glioma

YTHDF2

YTH domain family, member 2 

1p35

Longevity, susceptibility to [MIM:152430]

http://blogs.sun.com/ChinaExperience/resource/evolution.jpg

Are there any advantages to the Y chromosome evolving at such a rapid rate

The speedy rate, at which the Y chromosome is evolving at, is it beneficial in any way and is it showing

Most male individuals will agree that we are evolving faster and they would back this up with the investigation conducted by Whitehead Institute researchers proving the evolution in Y chromosome. Yet is literal evidence to back this up. When looking at "men vs. Woman", in work place, on the roads, in government who comes out on top. When looking educational credentials in the developed United States of America, for every three female college graduates there are only two males. A similarly uneven outlook on graduates of the rest of the developed world could be formed. (1) Pointed out in an article last year (April 22, 2008), that woman hold more degrees then men, they just have more trouble acquiring the job. More women are starting businesses than men. Yet 2007 statistics shown by Department of Labour showed that, women are only dominating fields and industries often seen as "female" industries. (1) So are men better drivers then woman If men were evolving faster than woman then technically basic thing as driving men should be better. Statistic shows that more men are involved in traffic violations and accidents then woman. (2)

Violations for which men scored at least 50 percent higher than woman (2)

TYPE OF VIOLATION

RATIO M:F

Reckless driving

3.41

DUI

3.09

Seatbelt violations

3.08

Speeding

1.75

Failure to yield

1.54

Stop sign/signal violation

1.53

So if statics show woman are better drivers then men and not only this but showing the there are less DUI's (driving under the influence) woman are more responsible. (2)

Fatal passenger vehicle crash involvements per 100 million miles traveled, by driver age and gender, April 2001-March 2002:

Age

Male

Female

16-19

Crash Involvements: 4,257

Miles: 46,427,394,010

Rate: 9.2

Crash Involvements: 1,852

Miles: 35,264,476,105

Rate: 5.3

20-29

Crash Involvements: 8,949

Miles: 225,999,581,860

Rate: 4.0

Crash Involvements: 3,172

Miles: 156,283,683,955

Rate: 2.0

30-59

Crash Involvements: 15,027

Miles: 845,507,965,689

Rate: 1.8

Crash Involvements: 6,946

Miles: 551,350,306,430

Rate: 1.3

60-69

Crash Involvements: 2,097

Miles: 128,814,817,845

Rate: 1.6

Crash Involvements: 1,008

Miles: 64,778,212,790

Rate: 1.6

70-Plus

Crash Involvements: 3,148

Miles: 76,991,652,560

Rate: 4.1

Crash Involvements: 1,571

Miles: 39,093,332,009

Rate: 4.0

Total*

Crash Involvements: 33,733

Miles: 1,324,373,970,682

Rate: 2.5

Crash Involvements: 14,633

Miles: 847,734,931,097

Rate: 1.7

Y-chromosomal Adam (Y-MRCA)

Y-chromosomal Adam is a scientifically-proven theory that every single man alive today descended from one male. Y-chromosomal Adam is the most recent common ancestor in human genetics. It is believed the he lived between 90,000 and 60,000 years ago in Africa. Y-chromosomal Adam lived much later the "mitochondrial eve", possibly 50,000 to 80,000 years later. (Mitochondrial Eve, all woman descended from her). (1+3)

Scientific evidence acquired by Spencer Wells (Geneticist) has proven that all humans alive today are patrilineally descended from a single man who lived in Africa around 60,000 years ago. (1)

Misconceptions arise since Y-chromosomal Adam is named after Biblical Adam which led people believing that Y-chromosomal Adam was the only living male. In fact he co-existed with many males. Yet all these male contemporaries were unable to produce a direct unbroken male line to the present day. "Population genetics states "Y-chromosomal Adam was not the common ancestor of the entire population"" (1). It's believed that in the future one of descendants may take over. Male lines do die out this leads to new individual become the Y-MRCA. Patrilineal lines are not likely to die out in times of rapid growth which we are presently in then during population bottle neck. (1) (Patrilineal lines, is nearly an infinite line of fathers).

Results published in 1995 by journal Science showed that there was no variation in the human Y-chromosome of 38 men from different ethnic groups (Dorit, R.L., Akashi, H. and Gilbert, W. 1995. "Absence of polymorphism at the ZFY locus on the human Y chromosome." Science 268:1183-1185). The segment of Y-chromosome analyzed consisted of 729 base pairs and all 38 analyzed no variation was shown. (3) The conclusion which arose was that human race must have experienced a genetic bottleneck sometime in the not too distant past. (3)

Yet what does it mean to be evolved or evolving

Definition of evolve; "develop via evolutionary change: in evolutionary theory, to develop from an earlier biological form" (1).

To "develop from earlier biological form" links to Y-chromosome Adam. Evolution links to changes in populations over many generations. Evolution occurs due to two factors, process that constantly introduces variation in traits and process where these traits either become more common or rare. Mutation is the main cause of variation. This leads to altered genes being inherited by offspring. (2)

Therefore to be evolving is not necessarily beneficial in any way and to be evolved is just different from original biological form.

Conclusion

It is clear that the Y chromosome is defiantly evolving at faster pace compared to the rest of the human genome. This is proven by the research conducted by Whitehead Institute researchers. However this does not man are better than woman. Men might be more evolved yet this might not be beneficial in any way. To be evolved is to be different from original biological form. The reason being for this is the pace at which the Y chromosome is evolving at "changing/mutating".

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