1. The world’s animal and plant communities are dynamic, not static: they change over time with new forms originating and others becoming extinct.
2. The evolutionary process is gradual and continuous. New species arise through slow and steady environmental changes that gradually ‘perfect’ each species to its surroundings. When sudden and dramatic changes occur in the environment, a species’ ability to adapt is usually challenged. Some species adapt and live; others become extinct.
3. All organisms descended from an original and common ancestor. Over time, the process of natural selection has created different species, each specifically adapted to its ecological niche.
4. Natural selection not only causes changes within populations during changing environmental conditions but also acts to maintain the status quo under relatively constant environmental conditions.
Concordance rates between MZ and DZ twins for (a) attitudes and (b)
personalities
Source: Adapted from Olson, J.M., Vernon, P.A., Harris, J.A., and Jang, K.L. The heritability of attitudes: A study of twins. Journal of Personality and Social Psychology, 2001, 80(6) 845–860, copyright 2001 by the American Psychological Association, reprinted with permission.
Source: Adapted from Olson, J.M., Vernon, P.A., Harris, J.A., and Jang, K.L. The heritability of attitudes: A study of twins. Journal of Personality and Social Psychology, 2001, 80(6) 845–860, copyright 2001 by the American Psychological Association, reprinted with permission.
Concordance rates between MZ and DZ twins for (a) attitudes and (b)
Source: Maisey, D.S., Vale, E.L.E., Cornelissen, P.L. and Tovee, M.J., Characteristics of male attractiveness for women. The Lancet, 1999, 353, 1500, reprinted with permission from Elsevier.
Source: Harris, C.R., Sexual and romantic jealousy in heterosexual and homosexual adults. Psychological Science, 2002, 13(1), 7–12, reprinted by permission of Blackwell Publishers Ltd.
