Evolution has resorted to some sort of universal formula for turning non-monogamous species into monogamous species by increasing the activity of certain genes in the brain and reducing that of others, according to a group of established American biologists.
To demonstrate this, researcher Rebecca Young and her colleagues at the University of Texas at Austin studied the genetic profile of 10 vertebrate species. “Our study spans 450 million years of evolution, which is how long ago all these species shared a common ancestor ,” says Young.
What is monogamy?
Monogamy can certainly be defined in several ways. In this study, the scientists define it from three specific behaviors in a couple.
- The presence of a link between two animals during at least one breeding season.
- Sharing the task of rearing offspring.
- The defense of babies against predators and other dangers.
In addition, the researchers still consider animals to be monogamous even if they occasionally mate with another animal.
The research team compared the gene expression of 10 pairs of closely related animal species, ie four mammals, two birds, two frogs and two fish; half of the pairs of different species were monogamous and the other half not.
Their goal? To determine if there are changes in each of the evolutionary differences associated with monogamy in related animals.
The comparison of the DNA of these vertebrate species allowed us to associate 24 genes with the fact that a male remains with the same female. According to Rebecca Young, hundreds of others could also have smaller effects.
According to the authors, these results suggest that evolution has used the same biological trick to turn certain species into monogamous species, simply by modifying the activity of these genes in the brain. Thus, despite the complexity of monogamous behavior, the researchers found that the same changes in gene expression occur each time.
Results also suggest that there is some connection between how complex social behaviors manifest themselves and how genes are expressed in the brain. “Most people would not expect that, for 450 million years, transitions to such complex behaviors would occur in the same way each time,” says Rebecca Young.
The study also found that genes involved in neural development, cell signaling, learning, memory, and cognitive functions were all more active in monogamous males than in non-monogamous males.
This may be due to the fact that animals must recognize their partners, offspring or the place they share with their partners, say the authors, whose work is published in Proceedings of the National Academy of Sciences.