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Asked by Finn to Barbara, Matt, Ravinder, Sophie, Tristan on 13 Mar 2015.
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Sophie Robinson answered on 13 Mar 2015:
Well, luckily we don’t really just ‘lose’ genes once we are formed. Genes can become deleted from the DNA when we make gametes, sperm or eggs, during errors in a process called meiosis. Meiosis is what happens when your cells divide to make sperm or eggs and sometimes errors can occur when the chromosomes cross over.
Also the male sex chromosome, the Y chromosome that makes someone male rather than female, is slowly deteriorating and could disappear completely within a few million years. Today, the human Y chromosome contains less than 200 genes, while the human X chromosome contains around 1100 genes.
Most of the genes on the Y chromosome have died because they weren’t essential. There is a chance that the Y chromosome eventually could disappear! But don’t worry, this probably isn’t the end of males! If the Y chromosome does disappear completely, a pair of non-sex chromosomes likely will turn into new sex chromosomes.
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Matthew Moore answered on 15 Mar 2015:
It depends what the gene did! There are other organisms, bacteria which actually use this as a tactic! Pseudomonas aeruginosa during infection will actually lose genes, mutations which break the gene altogether will convey an advantage for survival!
These genes that have been switched off, effectively lost, still reside in the DNA as a fossil called pseudogenes. There is good evidence that much further back during human evolution this happened quite a bit!
If you personally lost a load of genes tomorrow you’d probably be in big trouble. Evolution happens really slowly and so massive changes such as that are more likely to be problematic than helpful! Natural selection occurs by the slow gradual positive changes.
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