The importance of the domestication of horses to human civilisations is undisputed. But there are conflicting hypotheses about the origins of tamed horses; the 'restricted origin' hypothesis postulates selective breeding of a few founding lineages followed by distribution, while the 'multiple origins hypothesis' suggests independent recruitment of a large number of founders over an extended time period and geographical location. In the January 19
Infected with Wolbachia, the insects are expected to reduce the spread of dengue and Zika. But scientists say the approach may have limitations.