Narrator: Vermeij reasoned that if the predators of these marine animals were weak it also meant that there was no reason for those animals to waste energy building up thick protective shells. This was the observation that starting in the 1980s, put Vermeij on the path toward the scientific theory that would eventually bring him worldwide acclaim in his field: the escalation hypothesis.
Vermeij: So that got me thinking about escalation between species and their enemies. Well, escalation obviously was going on in international relations at the time with nuclear weapons and so forth. It got me to think – how do these episodes of escalation in nature as well as in the human realm. How do they get started and how do they end?
Narrator: So we traditionally think of evolution as the survival of the fittest meaning that the animals that are most able to feed themselves and reproduce are more likely to pass on their specific genes to the offspring. For instance a hummingbird with a bill that is best suited for extracting the nectar will be the so-called fittest in the group. It will eat we, be strong and reproduce. But is that all that affects their evolution? Well the escalation hypothesis says that evolution of one species doesn’t happen in isolation from other species. Vermeij’s idea is that when we try to understand the changes in hummingbirds we also need to look at their predators and their food sources. If predators that feed on hummingbirds, such as snakes or bats, are evolving and becoming stronger, the hummingbirds have to adapt. The same goes for snails and their predators. So Vermeij’s ideas caught on, and are now part of the standard canon of paleobiology, as Carmi confirms:
Carmi: It’s taught in class as one of the big paleo theories when you take an intro to paleo class.
Vermeij: I came to realize that this whole business of evolution and ecology, it all is based ultimately on economic principles of competition, cooperation, resources and redistribution and so forth.
Narrator: Vermeij explains that an organism has only so much energy that it can use for feeding itself or for protection. For instance the thickness of a shell can protect it from predators, but it also takes time and energy to grow. So if the predator, a fish or crab, is weak, then there is no reason for a snail to grow a thicker shell. But as crabs evolve to be more apt at getting access to the snails, the snails with thicker shells will be able to survive, so a thick shell becomes a desirable trait once again. Imagine this process as a pendulum swinging back and forth, back and forth. It’s never ending, this escalating competition between predators and prey.
Vermeij: You know years later I came to realize that the longterm historical trends that we see in the history of life are repeated on a shorter timescale in the history of humans. There’s not just parallelism, there’s very fundamental, very deep parallels between these two systems for the same reason, that they are guided by the same principles.
Narrator: Vermeij observed the same escalation in humans because he was growing up during the Cold War. As the Soviet Union poured more resources into its army and weapons, American military had to evolve as well. (In 1991, however, the Soviet Union fell apart and the escalation could slow down. Now, as the pendulum swings back again it seems that the tensions between US and Russia are intensifying. So in many ways humans are no different from snails – everyone is just trying to survive and possibly dominate.
Vermeij: So I’ve always wanted to study big issues as well as the details. What can shells and their enemies for example tell us about general principles and general rules and trends, etc.? That’s been a large part of my career and continues to be
Narrator: For Scienceline, this is Polina Porotsky