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We are sur­vival machines — robot vehi­cles blind­ly pro­grammed to pre­serve the self­ish mol­e­cules known as genes.” - Richard Dawkins, biologist

The study of deoxyri­bonu­cle­ic acid (DNA) allows sci­en­tists to unlock the secrets of our ances­tors and pre­dict how we might evolve in the future.

DNA is a chem­i­cal that resides in the nucle­us of every cell in our bod­ies. It con­tains a com­plete set of genet­ic instruc­tions for build­ing a body and con­trol­ling its metabolism.

DNA not only con­tains the human’s anatom­i­cal blue­print – plans for details like two legs, two arms and hair on the head – but also spe­cif­ic instruc­tions for build­ing each per­son as a unique individual.

Your DNA con­tains details for things like how big your feet should grow, what colour your eyes will be and even whether you can twist and roll your tongue or not.

Unfor­tu­nate­ly, DNA can also car­ry genet­ic defects that are harm­ful to us – such as a risk of devel­op­ing dia­betes or cancer.

By study­ing a par­tic­u­lar type of DNA called mito­chon­dr­i­al DNA” (mtD­NA), sci­en­tists can trace all mod­ern humans to a sin­gle com­mon female ances­tor who lived about 200,000 years ago – and she’s from Africa.

So how can sci­en­tists tell from DNA that mod­ern humans orig­i­nat­ed in Africa? Geneti­cists have found that mito­chon­dr­i­al DNA (mtD­NA), trans­mit­ted only from moth­ers to their chil­dren, pass­es almost unchanged from gen­er­a­tion to generation.

The slight changes that do occur result from muta­tions that geneti­cists think have been devel­op­ing at a con­stant rate through time.

By mea­sur­ing the amount of change in mtD­NA in mod­ern pop­u­la­tions, it is pos­si­ble to trace human geneal­o­gy over thou­sands of gen­er­a­tions, back to a com­mon female ances­tor of all liv­ing humans.

When sci­en­tists have test­ed cer­tain African groups, par­tic­u­lar­ly the Khoisan peo­ple in South­ern Africa and cer­tain oth­er pop­u­la­tions in East Africa, they have found more vari­ety in their mtD­NA than in pop­u­la­tions liv­ing out­side Africa. That means those Africans have been around for more gen­er­a­tions than any oth­er peo­ple, accord­ing to DNA evidence.

The DNA stud­ies cor­re­late with fos­sil dis­cov­er­ies which sug­gest mod­ern humans, Homo sapi­ens, have been liv­ing on the African con­ti­nent longer than any­where else. The old­est fos­sil evi­dence of mod­ern humans thus far has been found in Ethiopia and South Africa.

This sup­ports the Out of Africa” the­o­ry, which argues that humans orig­i­nat­ed in Africa and then spread to pop­u­late the rest of the world.

Return to the Exhi­bi­tion Guide.