Life sciences: biodiversity
The following excerpt from our exhibition guide is a good look at how biodiversity has developed since the beginning of the planet.
Scientists regard Africa as a remnant of the Earth’s past diversity. Its relatively sparse human populations until now have allowed people and a great range of other species to co-exist. But this is changing fast. The amazing biodiversity of life on Earth is now under serious threat.
About 600-million years ago, the first sponges, jellyfish and flat worms appeared in the oceans. The first arthropods – millipedes and centipedes, and later spiders and scorpions – moved onto land about 450-million years ago. Insects first evolved about 400-million years ago and reptiles about 330-million years ago. The first mammals appeared about 220-million years ago, and the first birds about 150-million years ago. The first flowering plants began to grow about 118-million years ago. The last dinosaurs were wiped out about 65-million years ago, and the first primates – our ancient ancestors – appeared about 55-million years ago.
However, hundreds – possibly thousands – of species are becoming extinct every year. Some estimates put the number of species dying out at about 100 every day; even conservative records of extinctions run to more than 500 a year. Currently, classified species include 4 000 different mammals, 9 000 birds and 750 000 types of insects.