Some Human Genes are 'Foreign' in Origin and Not from Our Ancestors

Scientists have discovered that humans may have some "foreign" genes that they've acquired from microorganisms co-habiting their environment in ancient times. Now, they've used their findings to challenge the conventional view that animal evolution relies solely on genes passed down through ancestral lines.

The transfer of genes between organisms living in the same environment is known as horizontal gene transfer (HGT). This is well known in single-celled organisms and is thought to be an important process that explains how quickly bacteria evolve resistance to antibiotics. However, HGT is also thought to plan an important role in the evolution of some animals, including nematode worms, which have acquired genes from microorganisms and plants, and some beetles that gained bacterial genes to produce enzymes for digesting coffee beans.

Now, scientists have found that HGT doesn't only just apply to primitive organisms. They studied the genomes of 12 species of fruit fly, four species of nematode worm and 10 species of primate, including humans. They calculated how well each of their genes aligns to similar genes in other species to estimate how likely they were to be foreign in origin.

In humans, the scientists confirmed there were 17 previously-reported genes acquired from HGT and 128 additional foreign genes that had not previously been spotted. This, in particular, shows that this phenomenon is far more common than previously thought.

In fact, the scientists believe that their analysis underestimates the true extent of HGT in animals and that direct HGT between complex multicellular organisms is also plausible. This reveals a bit more about the process of evolution.

The findings are published in the journal Genome Biology.

For more great science stories and general news, please visit our sister site, Headlines and Global News (HNGN).