A Salute to our Placoderm Pioneers: The first time vertebrates had sex

With the help of extremely rare, well-preserved fossils, we can trace complicated sexual behaviours back to ancient armoured fishes called placoderms.

Whether it is the conspicuous and cumbersome tail feathers of a peacock or the boisterous and bloody battles of male elephant seals, sex undoubtedly comes at a cost. Finding a mate can use up a lot of energy and involves taking risks. From an evolutionary point of view, sex is not an efficient way of sharing genes, passing only 50 percent of a parent’s genetic material on to the next generation.