Is it pos­si­ble for hu­mans and chim­panzees to in­ter­breed?

Focus-Science and Technology - - Q&A - PAULINE HETHERINGTON, SUR­REY

Ge­netic anal­y­sis sug­gests there may have been a long pe­riod of cross­breed­ing be­tween early an­ces­tors of the hu­mans and chim­panzees, be­fore they fi­nally split into the Homo and Pan (chimp) gen­era around six mil­lion years ago. But to­day, al­though hu­mans and chim­panzees share 99 per cent of the DNA se­quences that code for pro­teins, that DNA is pack­aged dif­fer­ently into the chro­mo­somes. The hu­man chro­mo­some num­ber two is ac­tu­ally two ape chro­mo­somes joined end-to-end, and nine other chro­mo­somes have in­verted se­quences of genes com­pared with their equiv­a­lents in chimps. Hu­mans and chimps also have dif­fer­ences in their in­di­vid­ual genes that are far big­ger than the dif­fer­ences be­tween any two un­re­lated hu­mans.

These are big ob­sta­cles, but not nec­es­sar­ily in­sur­mount­able. Other an­i­mals with com­pa­ra­ble ge­netic dif­fer­ences, such as ze­bras and horses, have bred suc­cess­fully in the past, al­though the off­spring are al­most al­ways ster­ile. There are doc­u­mented cases of So­viet ex­per­i­ments in the 1920s where ar­ti­fi­cial in­sem­i­na­tion was at­tempted us­ing fe­male chimps and hu­man sperm. How­ever, none of these ex­per­i­ments re­sulted in a preg­nancy, much less the birth of a ‘hu­manzee’. There are var­i­ous ur­ban le­gends of other later ex­per­i­ments in dif­fer­ent labs world­wide, but there’s no evidence that the re­sult was ever any dif­fer­ent.

Chimp skull (left) com­pared to a hu­man

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