Darwin's theory of evolution confirmed: the moth changes color to adapt to the environment

Scientists from the University of Exeter (United Kingdom) have shown that the spotted moth, also known as 'Darwin's moth' for having been identified as an evolutionary example, uses its color to better camouflage itself from the birds that feed on them, which caused them to darken when industrial pollution blackened British forests in the nineteenth century.

"It is one of the most emblematic examples of evolution, but fiercely attacked by creationists who seek to discredit the theory of evolution," says Martin Stevens, of the Center for Ecology and Conservation of the Penryn Campus of the University of Exeter. The study has been published in the journal Communications Biology.

The mottled moth or butterfly of the birches (Biston betularia) owes its name to this tree, whose trunk it uses to camouflage itself before the predators. In the 19th century, with the Industrial Revolution and the atmospheric pollution produced by the coal dust, the bark of the trees darkened, which also caused the moths to darken.

This phenomenon, called industrial melanism, in which the darker varieties prevail in contaminated areas, served to demonstrate Charles Darwin's theory of evolution by natural selection, being a subject of debate between evolutionary and creationist biologists. Afterwards, the disappearance of the coal dust pollution returned to harmonize the amount of lighter moths, which were majority before the Industrial Revolution.

The study by the University of Exeter has shown that moths manage to camouflage themselves in the trunks of trees effectively to the vision of predatory birds. "Using digital image analysis to simulate bird vision and field experiments in British forests, we compare the ease with which birds can see dark and pale butterflies, and determine their risk of predation," explains Professor Stevens.

"Our findings confirm the conventional history presented by the first evolutionary biologists: that the changes in the frequency of dark and pale butterflies were due to changes in pollution and camouflage," adds the Exeter researcher.

An investigation could rewrite part of the theory of human evolution

The new hypothesis indicates that the species progressed in dispersed and isolated populations from the extreme south to the coasts of North Africa, and not from a single and concentrated population.

A group of researchers from the University of Oxford determined that the human species evolved at first in dispersed and isolated populations in Africa, contradicting the usual narrative.

The extended theory defends that "Homo sapiens" progressed from a single ancestral population in a region of Africa about 300,000 years ago.

However, the team led by the University of Oxford scientist Eleanor Scerri concluded that the first humans understood a pan-African meta-population "subdivided, changing and with physical and cultural diversity".

"This fits with a subdivided population model in which genetic exchanges are not random or frequent and allows us to begin to detail the processes that shaped our evolutionary history," Scerri said, according to the specialized journal Cell Press.

Natural barriers, such as rivers, deserts and forests, that separated these populations, created opportunities for migration and contact between groups that had previously separated.

The theory presented today, which points out that there was mixing and isolation of populations from the extreme south to the coasts of northern Africa, is more consistent with the fossil and genetic data than a single population model.

The analysis of fossils of "Homo sapiens" combined with inferences made from contemporary DNA samples suggested levels of early human diversity that supported the changing subdivided population model of the researchers.

"For the first time, we have examined all relevant archaeological, fossil, genetic and environmental data to eliminate field-specific biases and assumptions and confirm that a mixture of pan-African origin fits much better with the data we have," Scerri said.

In the future, according to the authors, this research will allow models of human evolutionary history to reject the simple linear progression of what might be called "archaic morphology" towards a more precise explanation of the complexity and irregularity involved in evolution.

"We are an evolutionary lineage with deep African roots, so to understand this history, we must re-examine the evidence from various sources without an a priori conception," concluded the scientist.