Adaptation

• Both a process and a type of trait

• Process whereby genetic changes occur over many generations in a population as a result of natural selection.

• A process in which a genetic based trait increases in frequencies due to it being beneficial. it allows an individual to survive and reproductively successfully

Important note: this advantage is connected to a specific environment, which means if the environment changes, so does the advantage (adaptation)

• Also the trait that results from these genetic changes

• Adaptations can come from both the process and the result

• Due to our ancestors we can exhibit these adaptations even if we don’t live in the area that adaptation came from. (Due to alleles (multi generational changes) passing from ancestors to generations)

Acclimatization

• Long term changes that occur within one’s lifetime in response to environmental stress.

• Developmental acclimatization: changes in organ or body structure during the growth of an organism. (Due to stress)

• Usually permanent changes

• Physiological acclimatization: physiological change that occurs over days or months (Response to stress)

• Usually temporary. If the stressor goes away so does the change.

• Acclimation

• Short term physiological response to an environmental stress

• Ways our bodies respond in the moments. This can occur quickly. For example, a person getting on a plane. Their breathing may begin to be deeper to get oxygen in the body.

Homeostasis

• Maintenance of an equilibrium of various metabolic functions in the body

• The chemical composition of the fluids in our body, body temp. Homeostasis helps maintain these things in our bodies.

Cold Responses

• Acclimation

• Increased metabolism

• Shivering

• If not fixed, things like frostbite and hypothermia can occur

• Physiological acclimatization

• Further metabolic increase

• Increased red blood cell count

• Vasoconstriction: In the face of extended cold, out blood vessels may constrict and move inwards in the body to conserve heat. (Help preserve core body temp) (both vasoconstriction and vasodilation occur)

Note: Vasodilation is

• Cycling of heat to and from extremities (“hunting response”)

• Adaptations

• More compact body form

• Shorter appendages

• Rounder head shape

• Narrow, high nasal aperture

• Epicanthic eye folds and cheek pads

• Helps keep face warmer

• Light skin color?

• Darker skin is prone to cold easily

• Also culturally adaptation

• In cold responses, both Allen’s rule and Berman’s rule play a part.

Heat Responses

• Acclimation

• Sweating

• Cools the surface of the skin and encourages air to circulate around the skin.

• Increased blood circulation to skin

• Helps let heat escape

• Physiological acclimatization:

• Decreased heart rate

• Helps the body cool easier

• Increase plasma in blood

• Helps prevent dehydration

• Increased sweating

• Adaptation

• Elongated bodies

• Longer appendages

• Longer, narrower heads

• Cultural adaptation

High Altitude responses

• Oxygen pressure in the air is lower and this is significant because as we move up from the sea level air pressure decreases

• The effect it has is that there is less oxygen pressure in the air, which makes it hard for the body to get oxygen.

• Less oxygen leads to hypoxia because there is less oxygen in the blood cells/body

• The responses we get from high altitude is biological in nature to humans

• Acclimation

• Increased respiration

• Increased heart rate

• Increased hemoglobin content in red blood cells

• Physiological and developmental acclimatization

• Increased number of capillaries

• Increased lung size

• Increased production of red blood cells

• Respiration rate returns to normal

• Enlarged right ventricle of heart

• Babies born with lower birth weight

• Adaptation

• Larger chest circumference

• Enlarged lung volumes

• Lower hemoglobin concentration in blood

• Greater cardiac output to brain and uterus (during pregnancy)

• Less intro-uterine growth retardation

• Birth weights closer to those at sea level

• Slower growth growth rates during childhood and adolescence

• Decreased incidence of Chronic Mountain sickness (CMS)

• A condition that occurs especially in adults and elderly after living in high altitude for an extended amount of time if you didn’t grow up in the environment. If you have CMS, May experience headaches, dizziness, shortness of breath, and severe cases memory loss/death

• This condition is a lot less prevalent for people who have adapted to living in high altitude for many generations and whose bodies have adapted in order to maintain homeostasis.

Summary

• Variation in human traits may reflect the environment encountered during your lifetime

• Acclimation

• Acclimatization

• Variations may also reflect natural selection for traits that were adaptive in your ancestors environment(s)

• Adaptation