Research

Why did dinosaurs die out? New theory

Some experts have long believed that the reasonThe extinction of dinosaurs 65 million years ago was the fall of a massive asteroid. However, a new analysis by a professor of psychology at the University of Albany suggests that dinosaurs were in trouble long before the asteroid fell. Professor and evolutionary psychologist Gordon Gallup and his former student Michael Frederick, now working at the University of Baltimore, argue that the appearance of toxic plants combined with the inability of dinosaurs to associate the taste of certain foods with danger has led to their population already drastically declining at the time of the asteroid’s fall .

Acquired taste aversion isevolutionary protection that can be found in many species, in which the animal learns to associate the consumption of a plant or other food with negative consequences, such as a feeling of illness. To explain the defense mechanism, Gallup cites rats as an example.

"The reason most attemptskilling rats was not successful, it is that, like many other species, they have evolved to cope with plant toxicity, ”says Gallup. "When rats encounter new food, they usually try only a small amount, and if they feel bad, they demonstrate a remarkable ability to avoid this food again because they associate the taste and smell of it with an unpleasant reaction."

Why did dinosaurs die out?

First flowering plants calledangiosperms, appear in fossils long before the asteroid collapses and right before the dinosaurs began to gradually disappear. Gallup and Frederick argue that as plants developed and toxic protection developed, dinosaurs continued to eat them, despite gastrointestinal upsets. Although there is uncertainty about when flowering plants became poisonous and how long it took to spread this trait, Gallup and Frederick note that their appearance coincides with the gradual extinction of the dinosaurs.

In addition to studying the spread of toxicplants during the life of dinosaurs, Gallup and Frederick investigated whether birds (which are considered descendants of dinosaurs) and crocodiles (also descendants) can acquire taste aversion. It turned out that the birds, instead of getting used to the taste, developed an aversion to the visual features of what made them feel bad. They knew what they should not eat in order to survive. In a previous study, in which 10 crocodiles were fed various kinds of meat, some of which were slightly toxic, Gallup found that, like dinosaurs, crocodiles did not learn to understand tastes.

“Although the asteroid was certainly important,the psychological deficit that made dinosaurs unable to refrain from eating certain plants had a serious impact on them, ”says Gallup. “The widespread view of dinosaur extinction associated with the asteroid’s fall implies that the dinosaur’s extinction should have been sudden, but the opposite is clear: dinosaurs began to disappear long before the asteroid’s fall and continued to fade away for millions of years after it.”