My Top 10 Science Stories of 2005 – #9

EVOLUTIONARY BIOLOGY

Was Lamarck Right?

By Davide Castelvecchi
Jean-Baptiste Lamarck was the French naturalist who thought that giraffes are tall because they’ve been stretching. At each generation, their necks would get just a little bit longer, as the giraffes try to reach higher and higher branches. Lamarck predated Darwin in some respects — he realized that species are not unchangeable and that they are able to adapt to their environment. But of course it took Darwin’s genius to figure that natural selection is the mechanism of adaptation. Changes that occur during your life — you tan if you move to a sunnier place, and perhaps if you stretch you’ll get taller — do not pass on to your offspring. Apart from random mutations, an organism’s genes are the same at the time of reproduction as they were at birth. So when Lamarck postulated tbat the so-called acquired traits can be inherited, he was wrong.

Or was he?

Take for example this recent research. Pregnant smokers, researchers announced in April, seem to increase the risk of asthma not just in their children — as was known before — but also in their grandchildren.

Biologists have known for a while that there’s more information carried on from one generation to the next than what’s in the DNA. The extra information is called the epigenome. In particular, the proteins that wrap around DNA in a chromosome, aiding or hampering the activation of a gene and the production of the corresponding protein, are occasionally passed on when DNA duplicates.

In July, a Spanish team of researchers published the results of a study on identical twins, showing that even when two individuals have exactly the same genetic makeup, the way some of their genes are expressed — meaning that genes may be “turned on or off” in an individual — can differ in subtle ways, presumably due to epigenetic changes that took place during a lifetime.

Even weirder is what researchers discovered in March: weedy cress, a banal plant, is able to inherit correct genes from two generations back, even when the generation in between had mutated versions of those genes. Scientists speculated that the plant is somehow able to use epigenetic information passed on by RNA to repair its faulty genes.

(Science magazine reported on more juicy epigenetics in the 16 December issue, here and here.)

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