Inbred cattle don’t look bad at all

A herd of feral cattle in northern England may be a rare example of how a tiny group can overcome the dangers of inbreeding. This Chillingham herd, now with 49 members, probably hasn’t welcomed new genes for 300 years. In long-term isolation of some other species, harmful mutations have degraded reproductive success.

However, the Chillingham herd seems to have a history of healthy calving, say Peter Visscher of the University of Edinburgh and his colleagues. In the Jan. 18 Nature, they report that genetic analysis shows greater uniformity than in any other known cattle herd. The scientists suggest that the homogeneity came from a natural purging of harmful mutations, as carriers died or failed to reproduce. Since disease resistance in mammals appears to rely on inherited differences, the researchers look forward to further study of this uniform cattle herd.