Researchers: Gonorrhea could explain why we have grandparents

Researchers: Gonorrhea could explain why we have grandparents

That’s the view of researchers at the University of California San Diego School of Medicine who published their findings in Molecular Biology and Evolution, Sky News reports.

This discovery supports a theory that would explain why humans, unlike the vast majority of the world’s animal species, tend to take care of their descendants.

These findings suggest that the wisdom and care of healthy ancestors may have been an important evolutionary advantage that we have compared with other ancient human species, says Ajit Varkey, professor of cellular and molecular medicine at the respective university.

The “grandmother’s hypothesis”

Humans are also one of the few species that survive after our ability to reproduce has disappeared.

This is often explained by the “grandmother’s hypothesis” – that is, older women provide important developmental support in raising children.

Researchers at the university in question previously discovered a group of human genetic mutations that support this hypothesis.

According to researchers, the mutations will help protect older adults from cognitive impairment, including dementia, according to Sky News.

It was developed to treat gonorrhea

But now the University of California, San Diego School of Medicine has made an amazing discovery about it.

Their findings suggest that these highly beneficial genetic variants were likely developed in response to controlling pathogens, particularly gonorrhea.

In this way, in the long run, they strengthened the role of ancestors in human society, the university wrote on its website.

Compared to chimpanzees and Neanderthals

The breakthrough in the study came after comparing the genomes of humans and chimpanzees.

Then it was discovered that humans have a unique copy of the gene for CD33, a receptor that picks up and transmits signals in the neuron’s environment.

The gene was not found in Neanderthals, among others, which means that humans somewhere along the evolutionary line picked up another mutated form of CD33.

A variant that protects against Alzheimer’s disease in old age, according to researchers.

For most of the different genes in humans and chimpanzees, Neanderthals usually have the same version as humans, so this was surprising to us, Varkey says in a university press release.

Gonorrhea bacteria have influenced evolution

This is where the gonorrhea bacteria come into the picture.

According to the researchers, the infectious disease may have affected human evolution.

Bacteria have the same polysaccharides that the CD33 receptor binds to, and thus can trick human immune cells into believing they are outside invaders.

The brain selects the same gene variant

The study claims that humans have inherited the mutated form of CD33 because it protects our reproductive ability.

But over time, the brain must instead “select” the gene variant itself and use its benefits to protect against dementia.

This, in turn, would explain and give more weight to the “grandmother hypothesis” — which is why humans, as the world’s more or less the only animal, continue to care for their grandchildren, according to the UCSD News Center.

It is possible that CD33 is one of many genes selected for its survival benefits against infectious pathogens early in life, but is then selected secondarily for its protective effects against dementia and other age-related diseases, says a science professor Diseases Bhaskar Gagnoux, who is also behind the study.

Photo: J. Cohen

Text: Editors