New evidence for Lamarkian genetics

When Darwin published the Descent of Man, one of the central revolutionary ideas of his work was that acquired traits were not inherited. On a practical level, this means that if you work very hard to get yourself in good physical shape and improve yourself mentally, your hard work will not bring any benefit to the genome of your children. They will be born the same regardless of your state of health at the time of conception.

This Darwinian genetic model (i.e. only genes matter and you can't change them) was a strong rebuttal to the dominant model of the time, Lamarkian genetics. The Lamarkian model, which assumed the inheritance of acquired characteristics, was dismissed by western cultures by the beginning of the 20th century, but it was used by the Soviet government to plan out their food crops program. The miserable failure of the program was seen as definitive proof that the Darwinian model was correct.

Still, we knew it couldn't be that simple, and since the 1940s a new field called epigenetics has been developing which blends characteristics of the Darwinian and Lamarkian models. Epigenetics is defined on wikipedia as "the study of inherited changes in phenotype (appearance) or gene expression caused by mechanisms other than changes in the underlying DNA sequence ." The basic idea is that genes expression can be modulated (genes can be turned on or off) without actually modifying any DNA.

A great new example of this is a recent study reviewed on Wired which found that diabetic mouse fathers can pass on diabetic traits to their children. For these mice, diabetes was certainly an inherited characteristic, but it was transmitted in a very Lamarkian way. This has profound implications for our society where an unsettling large percentage of people are obese. This study implies that you might now just be hurting yourself, your hurting your kids. In addition, there are the social aspects to consider (the nurture side of the nature vs nurture debate). Even ignoring any genetic changes, a child that grows up in a home with unhealthy eating habits modeled for him or her is most likely going to make similar choices when he or she grows up.

So what are the take home messages here? Firstly, science is great and awesome, but its important to realize that just because a scientist or group of scientists say something doesn't mean it's completely true, or even partially true. If something is important to you, read their work and try to understand their logic. Sometimes its very good, sometimes its not, but the fact that a group of intelligent people think something doesn't mean its correct.

Secondly, take care of your body, both for your sake, and the sake of your kids. If diabetic traits can be passed down, who knows what other genetic goodies you can give your children if you take care of yourself?