Can we do scientifically sound predictions of how life would have evolved if the asteroid that hit at Chicxulub 66 Myrs ago and killed the dinosaurs would have missed Earth? We know from the history of life and from studies of recent animals that evolution often takes similar directions. Natural selection favours the individuals that are best adapted to their environment. Often there are specific solutions how to adapt in an optimal way. Life tends to find these solutions by a trial-and-error process involving the mechanism of natural selection. One example from today’s world is perhaps how cars are built. Most cars today have very similar shape, particularly the front part. This is simply an adaption to optimal energy conservation. Similarly, almost all animals with a backbone that live in water preying on free-swimming animals have the same streamlined body shape. For example, dolphins (mammals), sharks (fish) and the ichthyosaurs (extinct sea reptiles) all evolved the same torpedo-shaped body.
Another classical example of convergent evolution are the horned dinosaurs like Triceratops, that in many ways were similar to today’s rhinoceroses. One is a dinosaur, the other a mammal, but both are big plant eating animals with large nose horns with which the males fight about territory and females.
In the book Dinosauriernas död, meteoriterna och livets väg the concept of convergent evolution is further discussed. The question is posed: could dinosaurs as intelligent as humans have developed on Earth if the Chicxulub asteroid had missed Earth? Can we learn something about how life has evolved on billions of planets in the universe from the history of life on Earth?
