Copyright New York Times

Researchers have now found an entirely new line of ancestors of modern humans  - the Denisovans- whose genes we carry.  Gains in DNA Are Speeding Research Into Human Origins – NYTimes.com The article contains speculation that the mating between different early humans allowed for the transfer of genes helping the immune system. However, the archaic immune genetic material may be responsible for autoimmune diseases such as multiple sclerosis, arthritis and diabetes.

Why mention this? The point is that whenever someone mentions the influence of genetics of obesity, the common retort is that ‘the gene pool doesn’t change so fast.” The problems with this answer are (a) as indicated by the above study we are still sorting out what exactly is in the gene pool, (b) it ignores other recent findings showing that there are changes occurring more recently in our genes, (c) it ignores the long, 300 year picture of increasing height and weight in humans, and (d) it ignores the strong, developing evidence of the intrauterine environment and epigenetics.

Further evidence has just come out in a study of obesity across three generations. The researchers found that BMI is highly transmissible across generations, and especially involving the maternal line. The fundamental link between BMI of mother and child was not explained by shared environmental factors alone. Both mothers and fathers contribute equally to the child’s height. This was a prospective study with data collected from 3 generations of one family, with data taken prior to pregnancy and in early childhood. The authors conclude, “BMI in early childhood may be transmitted through a combination of genetic and intrauterine effects possibly operating via epigenetic mechanisms”.  Body mass index and height over three gene… [BMC Public Health. 2012] – PubMed – NCBI