New genetic research is shedding light on the history of North American bison and revealing how centuries of human activity have changed the genetics of one of the continent’s most iconic animals. The study, published in the scientific journal Science, analysed 160 newly sequenced bison genomes, including DNA from 115 ancient animals and 45 modern bison. Researchers combined these findings with 52 previously published genomes to create an extensive genetic record spanning approximately 20,000 years. Led by researchers at the University of California, Santa Cruz, the international study involved scientists and conservation partners from across North America, including Canada. Researchers examined ancient DNA preserved in bones alongside genetic material from living herds to understand how bison populations have changed over time. The findings show that bison populations were once genetically connected across vast areas of North America. However, intensive hunting during the 19th and early 20th centuries drove the animals close to extinction. Their numbers fell from tens of millions to only a few hundred, severely disrupting their natural population structure. Although bison numbers have recovered to hundreds of thousands, many modern herds remain isolated from one another. This separation can increase the risk of inbreeding and make it more difficult to maintain healthy genetic diversity over generations. Interestingly, researchers found that the overall loss of genetic diversity was not as extensive as previously expected. Instead, much of the remaining diversity is distributed unevenly among separate herds, with individual populations carrying distinct genetic characteristics. The study also highlighted important differences between plains bison and wood bison. These two groups adapted to different environments, with plains bison historically inhabiting grasslands and wood bison living mainly in northern forests and parklands. Researchers found evidence that the two groups diverged approximately 3,000 years ago. However, conservation practices in the 1920s, including the transfer of plains bison into Wood Buffalo National Park, resulted in interbreeding that affected the genetic makeup of modern wood bison populations. The research also challenged the widespread assumption that cattle ancestry is common among modern bison. Scientists found cattle DNA in roughly one-third of the sampled modern animals, and the contribution was generally small, accounting for less than two per cent of the genome when present. Canada played an important role in the research. Samples came from bison populations in locations including Elk Island National Park, Wood Buffalo National Park, Ronald Lake and Wabasca in Alberta. Collections held by Parks Canada and the Royal Alberta Museum in Edmonton also contributed to the study. Scientists say the findings could help wildlife managers make better decisions about breeding and conservation. By understanding the genetic history of individual herds, conservationists may be able to reconnect isolated populations while preserving the distinctive characteristics of plains and wood bison. The research offers a new genetic framework for protecting the species’ future. It also demonstrates how ancient DNA can help scientists understand the consequences of past human activities and develop more informed strategies for restoring wildlife populations.