Evolution and Medicine

Transcription

1 Evolution and Medicine Wellcome Images DDT, a powerful insecticide, was once effective against malariacarrying mosquitoes. But mosquitoes breed quickly, and resistant varieties soon appeared. They now thrive. Humans have dramatic impacts on nature. These affect evolution. MRSA is a rapidly reproducing bacterium that has evolved to become resistant to many antibiotics. Annie Cavanagh/Wellcome Images

2 Young Darwin Mary Evans Picture Library Charles Darwin with his sister, Catherine. He was born at Shrewsbury in He had one brother and four sisters. Charles spent much of his childhood exploring the countryside, ever curious about nature. He was a poor student. At university he gave up medicine, then abandoned the idea of becoming a country vicar. Steve Satushek/Oxford Scientific Films Doug Martin/Science Photo Library His father, who was a doctor, despaired about Charles lack of focus. You care for nothing but shooting, dogs, and rat catching, and you will be a disgrace to yourself and your family. A friend drew him riding a beetle with a butterfly net. Syndics of Cambridge University Library

3 Darwin lived on Gower Street Darwin married Emma Wedgwood, his cousin, in They rented a house on Gower Street, near this hospital. Their first son, William, was born there. Science Source/Science Photo Library Charles and Emma named the house Macaw Cottage because it was decorated in red and yellow. Darwin loved jogging in the back garden. These years were highly productive, and Darwin built a reputation for serious and skilled scientific work. University College London George Shepherd, London University from Old Gower Mews. UCL Art Collections

4 Darwin s Family Joe Cain Bernard Francis Elizabeth Charles and Emma moved to Down House, Kent, in They were devoted parents to their ten children. Their home was filled with the sounds of playing, learning, and discovery. Syndics of Cambridge University Library Darwin s children helped with his research. They studied plants and insects. They catalogued and organised. Darwin closely observed his children too gathering data on human behaviour. Gustoimages/Science Photo Library

5 Voyage of the Beagle Science Photo Library Darwin sailed round the world on HMS Beagle from his gap years. He paid his own way, studying natural history and geology. He visited tropical rain forests in Brazil, glaciers in Tierra del Fuego, and climbed the Andes mountains. Tarn C Nguyen/Oxford Scientific Films Science Source/Science Photo Library Darwin lived as a cowboy among gauchos in Argentina. He witnessed the brutality of slavery and survived an earthquake. He wrote a best-selling book about his journey. Rita Ariyoshi/Oxford Scientific Films

6 The Galapagos Islands Mark Jones/Oxford Scientific Films Mark Jones/Oxford Scientific Films Splashdown Direct/Oxford Scientific Films HMS Beagle arrived at the Galapagos Islands in Darwin noted that each island had its own animal and plant life, including individual species of giant tortoise and finches. There was even an iguana that fed on seaweed in cold ocean waters. Geographically isolated, the Galapagos became important for studying the origin of species. Finches, for example, evolved distinctive beak sizes and shapes for different feeding habits on each island. But they are all related to a single species of finch on mainland South America.

7 Deep Time History of the Earth In Darwin s day, Britain led the world in geology and palaeontology. Fossil discoveries led geologists to think of Earth s history as a book of many chapters, the last being our present age. Mauricio Anton/Science Photo Library Roger Harris/Science Photo Library Joe Cain Darwin collected many fossils including Megatherium, a giant sloth, and Glyptodon, a giant armadillo. He also studied the formation of mountains. Photo Researchers/Science Photo Library Darwin struggled to understand the immensity of time In Earth s history and the variety of species once thriving but now extinct.

8 Origin of Species (1859) First, evolution occurs. Species alive today are related to those in the past in the same way children today are related to their parents, grandparents and great-grandparents. The Origin of Species is one of science s great works. It compiles a massive base of evidence and builds testable theories. Darwin argued two main points. Second, natural selection drives evolution. Even tiny differences can play crucial roles in the struggle for existence. Ian Hooton/Science Photo Library

9 Descent of Man (1871) David Gifford/Science Photo Library Thomas Henry Huxley said that humans should be placed among the great apes because their anatomy was similar. Darwin discussed human origins in The Descent of Man. He applied natural selection to human evolution and argued that humans evolved as a distinct species from some lower form. The Origin of Species provoked discussions and controversy about man s place in nature. Wellcome Library London Darwin observed that humans and animals share many social and mechanical skills. We now know that humans and apes share over 90 per cent of their genes. Tony Craddock/Science Photo Library

10 in Man and Animals (1872) Expression of the Emotions Syndics of Cambridge University Library Roland Mayr/Oxford Scientific Films Do animals have the same emotions as we do? Darwin suggested humans have certain expressions because they inherited them from ancestors who used them as signals for non-verbal communication. Anthea Sieveking/Wellcome Images The similarity of emotions, and our ability to read animal expressions, added more evidence of common descent. But only humans have the ability to blush. For Darwin this implied only humans had a sense of right or wrong.

11 Artificial Selection Darwin was a careful observer. Consider dogs. Here is his daughter Henrietta with Polly. Think of the many breeds and how much variation is found among individuals in every breed. Deborah Bardowicks/Oxford Scientific Films Syndics of Cambridge University Library Even slight variations can play a role in dog evolution. By carefully picking from varieties, a breeder can create new pedigree lines artificially. Almost any change seems possible. Manchester Daily Express/Science & Society Picture Library Darwin also learned about fancy pigeons and how breeders created exotic lines. He called this artificial selection. It was, he said, like the process underway in nature. Mary Evans Picture Library

12 Natural Selection Georgette Douwma/Science Photo Library Sometimes natural selection rewards cooperating groups such as meerkats and bees. Darwin believed natural selection drove evolution by forcing species to adapt or face extinction survival of the fittest. Tony Camacho/Science Photo Library Simon Fraser/Science Photo Library Other times it rewards individuals who compete against each other. The most vigorous males or those most attractive to females are more likely to mate and produce the most offspring. This is sexual selection. Martyn Colbeck/Oxford Scientific Films

13 Evolution in Action Claude Nuridsany & Marie Perennou/Science Photo Library Natural selection is easy to observe. Take the peppered moth (Biston betularia). Speckled varieties are well camouflaged on trees. Varieties with more solid colours are picked out by birds. Millard H Sharp/Science Photo Library But where air pollution blackens trees with soot, speckled moths stand out while solid moths are harder to spot. Natural selection reverses. David Fox/Oxford Scientific Films Mary Evans Picture Library Less pollution in recent years has seen a comeback of the speckled variety, whilst the solid variety has declined. Mary Hinkley/UCL Media Services