Lecture 5: Adaptations to Environment and Classification

Adaptive Significance of Human Variation

  1. Types of Adaptation to Environment
  2. Acclimatization
  3. Adult acclimatization. Ex. if you're an adult and move to a higher elevation region, your body will increase its hemoglobin production so you can carry more oxygen to breathe better. Once you move back to a lower region, your hemoglobin levels will go back to normal. Ex. if you stay out of sun, you will get a tan. Once you stay away from it long enough, your tan will eventually fade. This is a reversible process.
  4. Developmental acclimatization. Ex. babies born in higher elevation regions are born with larger lungs to have room to breathe better. This process is not reversible, as the baby will have large lungs for the rest of their life. But it is not genetic, so their kids won't have big lungs if they are born in lower region areas
  5. Evolutionary (genetic) change occurs over a long period of time, effecting a population
  6. Skin Colour, Solar Radiation, Vitamin D. Page 55 - 56, 81 - 84.
  7. Responses to Heat, Cold and High Altitude
  8. Heat: Our body produces sweat which helps naturally cools us down. it is a short term effect, which has an immediate response like tanning. A theory is that humans have a loss of body hair unlike monkeys as an adaptation to the heat.
  9. Cold: Our body takes a lot of energy to keep us warm. If you cold a lot, your body trying to heat you up will cause your metabolic rates to increase.
  10. Bergmann's and Allen's rules: Humans that like in high altitude populations like the Inuit, tend to be stocky with short limbs so they can preserve body heat. People in hotter climates have longer thinner limbs.
  11. High altitude: When you travel to higher altitude areas, your body creates more hemoglobin so that you can breathe better.
  12. Infectious Diseases Page 89 - 93.
  13. A zoonotic disease is a disease that is transmitted to humans through the contact of an animal.
  14. Influenza is a contagious respiratory disease caused by virus strains. Like HIV, is it a zoonotic disease because humans get through contact with pigs and fowls.
  15. The possible relationship between resistance to HIV/AIDS and Smallpox is that they come from the same mutation. A mutation that originally favoured by selection because it provides protection against one type of infection (Smallpox) can also increase resistance to another (AIDS).
  16. The main reason why death due to infectious disease on the rise is because the diseases become resistant to antibiotics. Some other reasons are because of poor sanitation and the overuse of antibiotics which leads to the virus become resistant overtime. Also, as the human population grows, we are faced with more environmental problems and global warming.


Two Major Organizing Principles

  1. Geologic time scale
  2. Formal biological classification was created to get a better understanding of evolutionary relationships and to organize diversity into groups to reduce complexity. It has to reflect evolutionary descent for it to be useful.

Classification Terminology

  1. Homologies are structures which are similar because the two organisms shared a common ancestor. Ex. the hands of humans and monkeys.
  2. Analogies aka homoplasy are structures which are similar because the two organisms live in similar environments, or the structure has the same function. The structure is adapted to better suit the environment. Ex. the fins of fish and whales. They have separate ancestors but the fins have similar functions and both organisms live in the same environment.
  3. Ancestral means the organisms share a common ancestor. It is important in understanding big groups. Ex. All primates have grasping hands while only monkeys, apes and humans have large eye sockets.
  4. Derived characters are modified from the ancestral groups. The organisms may be related a long time ago, but eventually became subgroups that are different. Ex. monkeys have tails that humans and apes have lost.

*For evolutionary studies, we need characters which are both homologous within the larger group and derivative between groups.




Approaches to Classification

  • Evolutionary systems and cladistics
  1. Similarities
  2. Differences

*Biological anthropologists use both, in different ways.

Genus and Species: Complications for Ancient Organisms

  • Biological species concept and paleospecies

Mammals and Mammalian Evolution

  • The Cenozoic epoch was the age of the mammals.
  • Success due to learning and flexible behaviour, based on:
  • Larger brains (encephalization)
  • Longer 'in utero' development
  • Longer attachment to parents
  • Heterodont dentition
  • Constant internal thermal temperature

Processes of Macroevolution

Adaptive radiation

Generalized and specialized characteristics

  • Read approaches to classification on page 99-100. Notes will be posted if not covered in class.

adaptive radiation finches britannica evolution

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