Scientists unlock mystery of environment’s control on animal sizes

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Scientists at McGill University have managed to unravel the mystery of how an animal’s growth is controlled by environment factors also known as epigenetic factors.

A team led by Professors Moshe Szyf and Ehab Abouheif, from the McGill’s Departments of Pharmacology and Therapeutics, and Biology respectively set out to identify a mechanism by which epigenetic factors have an overarching effect in creating quantitative variation in complex traits such as height, skin colour, tendency to gain weight or not, intelligence, tendency to develop certain diseases among others.

Researchers conducted epigenetic experiments on ants from the species Camponotus floridanus (better known as the Florida carpenter ant). The researchers increased the degree of DNA methylation (a biochemical process that controls the expression of certain genes – a bit like a dimmer can turn a light up or down) of a gene involved in controlling growth called Egfr, they were able to create a spectrum of worker ant sizes despite the lack of genetic difference between one ant and the next. Essentially, the researchers found that the more methylated the gene, the larger the size of the ants.

“Basically, what we found was a kind of cascading effect. By modifying the methylation of one particular gene, that affects others, in this case the Egfr gene, we could affect all the other genes involved in cellular growth”, said Sebastian Alvarado, the McGill PhD who is the co-first author on the study.

“It’s a discovery that completely changes our understanding of how human variation comes to be,” says Abouheif. “So many human traits, whether they are intelligence, height, or vulnerability to diseases such as cancer, exist along a continuum.”