PCDH11Y is a

gene In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...

unique to ''

Homo ''Homo'' () is the genus that emerged in the (otherwise extinct) genus '' Australopithecus'' that encompasses the extant species ''Homo sapiens'' ( modern humans), plus several extinct species classified as either ancestral to or closely relat ...

'' males that encodes

Protocadherin Protocadherins (Pcdhs) are the largest mammalian subgroup of the cadherin superfamily of homophilic cell-adhesion proteins. They were discovered by Shintaro Suzuki's group, when they used PCR to find new members of the cadherin family. The PCR fr ...

11Y, a

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...

that guides the development of

nerve cells A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozoa. ...

PCDH11X Protocadherin 11 X-linked, also known as PCDH11X, is a protein which in humans is encoded by the ''PCDH11X'' gene. Function This gene belongs to the protocadherin gene family, a subfamily of the cadherin superfamily. The encoded protein consi ...

, located on the

X chromosome The X chromosome is one of the two sex-determining chromosomes (allosomes) in many organisms, including mammals (the other is the Y chromosome), and is found in both males and females. It is a part of the XY sex-determination system and XO sex ...

, is common, in both sexes, to humans and our nearest relative, the chimpanzee; however, PCDH11Y, located on the

Y chromosome The Y chromosome is one of two sex chromosomes (allosomes) in therian mammals, including humans, and many other animals. The other is the X chromosome. Y is normally the sex-determining chromosome in many species, since it is the presence or abse ...

, is unique to males.''Science and Technology: The genetics of lateralisation''

The Economist ''The Economist'' is a British weekly newspaper printed in demitab format and published digitally. It focuses on current affairs, international business, politics, technology, and culture. Based in London, the newspaper is owned by The Eco ...

, 26 April 2001 In terms of human evolution, it has been estimated that pcdh11x " gene jumped" from X to Y around three million years ago; coincident with increased human

brain size The size of the brain is a frequent topic of study within the fields of anatomy, biological anthropology, animal science and evolution. Brain size is sometimes measured by weight and sometimes by volume (via MRI scans or by skull volume). Neur ...

and the first use of tools. Furthermore, around 120,000 to 200,000 years ago, the PCDH11Y gene was able to further transform, splitting in half and reversing its position.''Y and Mighty''

The Guardian ''The Guardian'' is a British daily newspaper. It was founded in 1821 as ''The Manchester Guardian'', and changed its name in 1959. Along with its sister papers ''The Observer'' and ''The Guardian Weekly'', ''The Guardian'' is part of the Gu ...

. 18 August 2001 PCDH11X/Y are cadherin family genes. They make proteins, involved in signalling, that attach to the surface of nerve cells. PCDH11X and PCDH11Y, respond in different ways to

Retinoic acid Retinoic acid (used simplified here for all-''trans''-retinoic acid) is a metabolite of vitamin A1 (all-''trans''-retinol) that mediates the functions of vitamin A1 required for growth and development. All-''trans''-retinoic acid is required in ...

, a chemical involved in the development of embryos. The acid stimulates the activity of PCDH11Y but suppresses PCDH11X. This is likely one of the explanations for the differences between the brains of men and women. Psychiatrist, professor Tim Crow, also believes the gene explains lateralisation. Humans have "lateralised" brains, in which the different sides became specialised for particular jobs. For instance 90% of people will use their right hands for fiddly tasks. A chimpanzee is just as likely to use either hand. It also explains why, for right-handed people, linguistic functions are concentrated on the left side of the brain.

References

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