Sex and cancer: why mankind really need sexual reproduction

Researcher of the laboratory of aging research at Harvard medical school and MSU Alex Tyshkovsky told why mankind really need sexual reproduction. According to the scientist, sex is a natural protection from cancer.

More arguments Myskovskogo you can see below.

Candidate of biological Sciences, founder and host of the Internet channel "Real Scientists" (Real scientists) Alex Tyshkovsky shared his opinion about why people actually have sex.

Alex Tyshkovsky

According to the scientist, many people mistakenly think that it is for pleasure or procreation. To some extent, they are right, but why sexual reproduction? Because living organisms can reproduce more simple ways, for example, the same budding.

However, people chose sex. And for good reason. Let's see why.

As an example, consider a hypothetical mutations of two ancient fish. One due to changes in the DNA were his feet. The second — formed lungs. If these two mutations were able to unite into one, the descendant of two fish could go ashore and safely to survive. But if fish were reproducing asexually, their descendants would have received only one mutation.

However, due to the "mixing" of genetic information that occurs during sexual reproduction, the offspring of these fish could get two mutations at once. It is an undeniable advantage of this type of reproduction, as it increases the diversity of offspring and accelerates evolution.

In addition, sexual reproduction allows the offspring to separate the "harmful" mutations from "useful". For example, in maternal DNA originated from two mutations: one useful and one harmful. If reproduction happened asexually, the offspring would get both of these mutations. Accordingly, in the future, they would be passed to the rest of the offspring until his disappearance. But thanks to sexual reproduction, a child can get rid of the "genetic noise", having only half the genetic material of the parent.

By the way, that is why it is so important that parents were distant from each other in the genetic sense, in other words, were not relatives. Otherwise, mixing their DNA can lead to unpleasant consequences. The most common risks associated with incest include the susceptibility of children to infectious diseases and their failure to conceive.

Considering all the above advantages of sexual reproduction, it becomes clear why the vast majority of living organisms are practicing it.

Another indisputable advantage of sexual reproduction is that it can be used to protect against cancer. Yes, Yes, all is well! Giving their offspring the genetic diversity, we thus helps them to resist cancer. How? By creating a new immunity.

Fortunately, the man can't catch cancer from another person. But Tasmanian devils and dogs are less fortunate. These mammals cancer can transmit through bites. For dogs, this does not usually entail serious consequences, but from the Tasmanian devil, the situation is much worse... Over the last 20 years their population decreased by 80%, and, according to scientists, the reason was a cancer epidemic.

But as it turned out that cancer was an infectious disease for these animals? Most likely, this occurred due to low genetic diversity. In other words, if the cancer has adapted to the immune system of one organism, it is likely to adapt to another.

Therefore, in order to be protected from transmission of cancer, the animals must possess a high genetic diversity. It gives us sex.

In favor of this theory is the fact that as a result of asexual reproduction, the organism is a genetic copy of the parent with the exact same immune system. And, indeed, during the experiments, scientists managed to establish, that the offspring of the Hydra sometimes received from her cancer. In sexual reproduction, such cases were not recorded.

Therefore, we can summarize that the main advantage of sexual reproduction is to create a unique genotype. Thanks to him, there is a new immune system that can repel cancer cells. Perhaps that is why many years ago, multicellular animals (and us) refused all other types of procreation, giving preference to this.