Evolutionary scientists think same-sex sexual behavior is wrong.
That is the implication of the new study onwards same sex behavior in animals. Instead of asking why animals engage in same-sex behavior (SSB), researchers should ask, "Why not?" The authors said.
If they are right, sex may not have evolved independently in different animals for pleasant reasons. Instead, sex can occur very early in time and can persist simply because being involved does not cost many animals, evolutionarily speaking.
"Usually, when evolutionary biologists see a trait that is really widespread in the evolutionary lineage, we at least consider the idea that the trait is ancestor and is preserved in all those traces," said Julia Monk, a PhD candidate at Yale University authored the new research. "Well, why didn't people consider that hypothesis SSB?"
In evolutionary science, same-sex sexual behavior has long been considered a disease: Why do animals spend time and energy doing something sexual that won't pass on their genes to the next generation? And yet, same-sex sexual behavior has been reported in at least 1,500 species, ranging from mild squash errors to humans.
(To avoid anthropomorphization, researchers do not use the terms "homosexual," "heterosexual," "gay," or "straight" to refer to animal behavior.)
“We can not be attributed to animal sexuality – we try to do our best to learn about them by enhancing their behavior, "Monk told Live Science." And these behaviors should not be mapped onto human cultural and social contexts.
The assumption that there must be an evolutionary reason for all this sex has made researchers look for possible benefits from same-sex behavior. For example, in humans, researchers have found that having a gay son or brother seems to be related to a woman. they have more descendants in total. Other studies have suggested that same-sex intercourse is an adverse effect other genes which have reproductive benefits.
In evolutionary biology, the ability of an animal to reproduce in its surroundings is called fitness. It is quite possible that in some species, sex may also have fitness benefits, Monk and her colleagues wrote in their paper, published November 18 in the journal. Nature Ecology and Evolution. But these evolutionary benefits may not be needed for same-sex sexual behavior.
Imagine, imagine, that the early animals that reproduce sexually simply tried to associate with all members of their species – regardless of sex. This may be a logical path to evolution, because all the tunes and gigs that distinguish males from females are energetically expensive to develop. So any effort spent on same-sex mating will be offset by not wasting energy to develop and maintain characteristic secondary sex characteristics, as different colors, scents and behaviors. Gender-specific traits may appear later in the evolution chain, the authors argue.
In this formulation, same-sex and different sex behavior would begin on an equal footing, early in the evolution of animals. This may explain why same-sex sex is so common throughout the animal kingdom: It has not evolved multiple times on its own, but instead has been part of the fabric of animal evolution from the beginning.
The new hypothesis implies old assumptions about same-sex behaviors, said Caitlin McDonough, a Syracuse University doctoral candidate and co-author of the study. Much of the research done on these sexual behaviors assumes that sex is expensive for animals and that sex of different sex is not expensive, she said.
"You really have to go through those assumptions and test the costs and benefits of both behaviors in one system," McDonough said.
If same-sex behaviors go back to the roots of animal evolution, it makes sense that these behaviors are so common today, Monk said.
"If you assume a feature like SSB is a new development and has high costs, it will be really difficult to understand how it could become more common than those low initial frequencies," she said. "Would have had to have really great fitness benefits, or otherwise be impermeable to natural selection, for that outcome to be probable.
"On the other hand, if you assume that a trait is an advantage and was originally common, and has low costs, it is very likely that it will remain widespread to this day, even if it does not seem to contribute much to fitness. "
One evidence supporting this hypothesis is that some echinoderms, including sea stars and sea urchins, engage in same-sex sexual behavior. Echinoderms evolved early in the history of life, probably in the Precambrian period more than 541 million years ago.
But other evidence is thin, largely because scientists have not studied systematic same-sex sexual behavior in animals. Most of the observations are random, and biologists have often viewed sex between two animals of the same sex as irrelevant or inappropriate to detect, Monk said. Sometimes, researchers automatically assume that same-sex behavior is not about sex, but about domination or relationship. And, often, if two animals are found to have sex, they are assumed to be male and female without any conclusive evidence, McDonough said.
"The science we do is really informed and influenced by cultural biases," she said.
Thinking of same-sex sexual behaviors as a standard part of the animal repertoire will change the way researchers approach the study of the evolution of these behaviors. The next step, Monk said, would be to collect more data on the prevalence of same-sex animal behavior. Researchers could then compare species across the tree of life to determine if all coatings exhibit same-sex behavior. If so, it would reinforce the argument that same-sex sexuality is a part of life for the ancestors of all of today's sexually reproductive animals.
Originally posted on Live Science.