Snakes and Humans

A study done in Japan revealed that the saliva of all mammals, including humans, and the venom of snakes are descended from the same ancestor. The results showed that it is evolutionarily possible for humans to be poisonous, too.

Snakes, some lizards, and even a few mammals have the ability to inflict a venomous bite. Although it is known that the lineages of these poisonous creatures diverged 300 million years ago, according to a recent discovery, their venom actually came from the same ancestor. The research was published in the journal BMC Biology.

They focused on a class of venom found in most snake venom and all other reptilian and mammalian venoms, called kallikrein serine proteases, according to the published research. As a result of the studies, the ancestor of the poison class was revealed. Thus, it was revealed that the poison in these creatures came from a common ancestor.

The idea was first put forward as a hypothesis:

This study by the Graduate University of Science and Technology in Okinawa and the University of Australia in Japan actually drew on the results from the previous study. In their previously published studies, scientists discovered that the mammalian salivary gland and snake venom gland have the same activities in a group of regulatory genes. This showed that the basis for the development of the venom was present in both snakes and mammals.

With this study, the existence of a group of genes with venom potential in the ancestors of snakes and mammals was presented as a hypothesis. According to this hypothesis, both creatures followed different evolutionary paths. Mammalian venom has evolved, but not so much. After this research, scientists started a new study to discover the ancestors of the two living things.

After advances in gene research methods, scientists compared the kallikrein gene found in reptiles, amphibians, fish, and mammals to finally construct an evolutionary tree. The results proved that snake venom in the saliva of mammals came from the same ancestor.

This resulting evidence suggests that it is possible, through evolution, for salivary kallikrein proteins in mammals, including humans, to become toxic as well. However, the fact that the building block that develops the poison is in our genes does not mean that it will definitely happen.