Wild pig plague is evolving rapidly

Animal species can sometimes evolve very quickly. Biologist Niek Barmentlo discovered that this is now happening in North America. Wild pigs have adapted to their environment and are now overrunning the United States.

We see evolution primarily as a process lasting millions of years, with a complex animal as the ’result’. But for a biologist, evolution is nothing more than a shift in the genetics of an entire population, something which can happen very quickly. In Mozambique, for example, many female elephants are born without tusks. This is due to poaching: elephants are killed so often for their tusks that it has become an advantage not to have tusks.

Evolutionary traces in DNA

This rapid evolution leaves traces in the DNA of the animals. Normally you see many different alleles: versions of a gene in a population of wild animals. With rapid evolution, the number of alleles decreases considerably. In their study, which appeared in Molecular Ecology , Barmentlo and his co-authors applied this principle to an animal species currently sweeping North America: the wild pig.


Pigs came to America from Europe around 1500. About 100 years ago, wild boars were also added. That did not cause any problems until about 40 years ago. The populations suddenly grew enormously and caused a lot of damage. These were hardly pure pigs or wild boars, but often hybrids between the two: wild pigs. The animals are now in 39 of the 50 American states.

Surviving in a new place

Wild pigs are genetically very healthy due to hybridization. Their skull is a different shape than that of a pig or boar, and they are very smart. These are all’useful adaptations to survive in a new place. The researchers discovered that these properties actually change in the animals. Barmentlo: "We observed evolution on genes that are important for these traits. In fact, our analyses show that this is probably due to natural selection. The wild pigs really seem to be adapting."

This conclusion is not good news for everyone: the wild pigs damage ecosystems. They cost the United States at least $1.5 billion a year, and probably many times that amount.