Human genes may have DNA from other living things.

Given what is known about genetic transmission and, of course, giving a good simplification, we all know that our genes are passed down from generation to generation, from parent to child. The information contained in our ancestors' DNAs has been going through the years, going from individual to individual vertically, as if we were connecting through a tree (hence the concept of family trees).

Horizontal gene transmission, called horizontal gene transfer (HGT), had already been witnessed by scientists among fairly simple life forms such as bacteria, algae and other single-celled beings. With the possibility of mapping the genome of living things, HGT was noted when, for example, researchers found parts of plant DNA and microbes in nematodes. Diatom algae, responsible for producing one fifth of the planet's existing oxygen, have bacterial genes passed on to them via horizontal transmission.

A more complex panorama

The presence of HGT in more complex beings has been proven in the study of beetles, which would use information brought by the DNA of certain bacteria to learn to digest food that these insects alone would not be able to consume.

So far so good. However, now researchers have come to the conclusion that we humans also have intruder DNA received horizontally. At least 145 genes found in us would not originally be human, but would have come from bacteria and protists.

Shaped by other people's genes

These genetic interferences would be the origin of complex things of our nature, such as the ABO blood system. In addition, it is speculated that certain characteristics involving digestion, immunity and metabolism are also linked to HGT. But not only that: we would also be spreading our genes around, as parts of our DNA would also have been found in the genome of other living things. Some bacteria may be building resistance against ourselves through the human DNA that has gotten into them.

Of course, much of this study is still being developed and it is logical that much of the scientific community still views it all with a skeptical eye or even refuses to accept that there is HGT involving beings as complex as we humans. Really or not, if this discovery is indeed legitimate, it will be necessary to completely revise the theory of evolution in the light of horizontal genetic transfers, which can alter the whole story of how we and all other species have come this far.