Aren’t epigenetic effects evidence for Lamarckism? © Getty Images

Aren’t epigenetic effects evidence for Lamarckism?

Giraffes’ necks are an evolutionary puzzle but what do they have to do with evolution?

Asked by: Sally Ellis, Manchester

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Not really. Epigenetics is when genes alter their activity in response to external factors such as diet, exercise and chemical exposure. The sequence of letters in the DNA doesn’t change, but the DNA molecule acquires other chemical changes that can be passed on to your offspring. These inherited traits last for two or three generations.

Lamarckism says the giraffe got its long neck because parents stretched their own necks slightly during their lifetimes and passed that increase on to their children, and so on. That’s quite different from the Darwinian view that each generation has a certain amount of natural variation, and that giraffes with longer necks have more offspring.

Epigenetics is an important influence on evolution, but it doesn’t drive long-term species change.


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