How evolution explains autism rates in humans

A paper in Molecular biology and evolution Notes that the relatively high rate of autism spectrum disorders in humans is probably due to the way humans have evolved in the past. The article is entitled “A general principle of neural evolution reveals a type of human accelerated human neuron potentially underlying the high prevalence of autism in humans.”

In the United States, approximately one in 31 (3.2%) was identified with autism spectrum disorder. Globally, the World Health Organization believes that around one in 100 children at autism.

From an evolutionary point of view, many scientists believe that autism and schizophrenia can be unique to humans. It is very rare to find behaviors associated with disorders of non -human primates. In addition, behaviors associated with these disorders generally involve cognitive features such as the production and understanding of speech which are unique or much more sophisticated in humans.

With the development of unique RNA sequencing, it has become possible to define specific types of cells through the brain. While investigators have published more -scale more data sets, it has become clear that the brain of mammals contains an amazing range of types of neural cells.

In addition, large -scale sequencing studies have identified extensive genetic changes in the unique brain with Homo sapiens – genetic elements that have not changed much in the evolution of mammals in general but quickly evolved in humans.

While previous surveys have revealed that certain types of cells have remained more consistent throughout the evolution than others, the factors stimulating these differences in evolutionary rate remain unknown.

Researchers have studied here on the unique RNA sequencing data games on the recently published inter-nucleus species from three distinct regions of the mammals brain. They found that the most abundant type of external layer cerebral neurons, IT neurons L2 / 3, has evolved exceptionally quickly in the human line compared to other monkeys.

Surprisingly, this accelerated development was accompanied by spectacular changes in the genes associated with autism, which was probably trained by a natural selection specific to the human line. Researchers explain that although the results strongly suggest the natural selection of genes associated with autistic spectrum disorders, the reason why this has given the advantages of fitness to human ancestors is not clear.

Responding to this is difficult because we do not know what characteristics specific to the man of cognition, brain anatomy and neural wiring have given human ancestors a fitness advantage, but researchers speculate here that many of these genes are associated with a delay in development, so their evolution could have contributed to the development of the slower postnatal brain in humans.

In addition, the capacity for production and understanding of single speech to humans is often affected by autism and schizophrenia.

It is possible that the rapid evolution of genes linked to autism has conferred a fitness advantage by slowing down the development of the postnatal brain or by increasing language capacity; The longer brain development time in early childhood has been beneficial for human evolution because it led to a more complex thought.

“Our results suggest that some of the same genetic changes that make the unique human brain also made humans more neurodivers,” said the main author of the newspaper, Alexander L. Starr.