Scientists say evolution is so random that if we could turn back time and let ancient human ancestors relive their entire path of development and genetic change, it would be very difficult for Homo sapiens to re-emerge.

A new study questions this thesis

The study of Batteridae shows that: Evolution can sometimes repeat itself in predictable waysThis can help us understand how organisms change in response to selection pressures.

Patrick Nosil, an evolutionary biologist at the French National Center for Scientific Research, and his colleagues studied the camouflage of spiny bugs, primarily Timema cristinae.

• Since the 1990s, Nosil and his colleagues have been catching these flightless insects along roadsides in the mountains near Santa Barbara, California.
• After 30 years of field research conducted in 10 different locations, they found that: replication is an important part of arthropod evolution.
• They only lay eggs once a year, so each year in the study represents a new generation of insects with no overlap.

The three varieties of T. cristinae are camouflaged with white bands or a solid green color that matches their preferred host plants or, more rarely, a dark shade.

By capturing and cataloging more than 32,000 insects, the team was able to track trends and found this across all 10 geographically separated populations. The frequency of green and striped sticklebacks varied predictably from year to year. Even though the number of strippers decreased in one year, it increased in the next and vice versa. However, the proportion of rarer black beetles mixed into the forest floor remained fairly low and stable over time.

Our results show that the evolution of the same trait is both iterative and complex.
– says the article.

The findings echo previous studies that tried to understand why evolution continues to produce (and not produce) crabs with lateral body plans, powerful shells, and massive claws. Research has also shown that other organisms, such as sticklebacks, have a similar tendency to evolve the same traits over and over again.

But Most of these conclusions are based on studies on one or more populations or on brief laboratory experiments.It is not long enough to capture the appearance of genetic mutations that could lead to the emergence of new useful traits.

This new research brings us back to the issue of determinism and randomness that has been debated for decades in the history of life, but it may have implications for the future. Scientists not involved in the study believe that understanding that evolution sometimes works in a predictable way could help researchers predict how organisms change and therefore manage populations.

But because Nosil and his colleagues examined only T. cristinae and its relatives, they can only speculate about how the results might be different in other species or whether evolution is predictable elsewhere in the animal and plant kingdoms.