Tuesday, March 27, 2012

Human variation and race

The effect of heat on our bodies varies with the relative humidity of the air.  High temperatures with high humidity make it harder to lose excess body heat.  This is due to the fact that when the moisture content of air goes up, it becomes increasingly more difficult for sweat to evaporate.  The sweat stays on our skin and we feel clammy.  As a result, we do not get the cooling effect of rapid evaporation. In dry, hot weather, humidity is low and sweat evaporates readily.  As a result, we usually feel reasonably comfortable in deserts at temperatures that are unbearable in tropical rain forests.  The higher the desert temperatures, the more significant of a cooling effect we get from evaporation.

A short term adaptation, as stated above, to this is sweating. The warm water evaporates off of your skin very quickly, bringing the heat with it.


A facilitative adaptation is to have the ability to physiologically acclimatize to hot conditions over a period of days to weeks.  The salt concentration of sweat progressively decreases while the volume of sweat increases.  Urine volume also reduces.  In addition, vasodilation of peripheral blood vessels causes flushing, or reddening, of the skin because more blood is close to the surface.  That blood brings heat from the core body areas to the surface where it can be dissipated easily into the environment by radiation.



A developmental adaptation to this is that some human nerve cells have proteins on their surfaces that enable them to differentiate between several different temperatures in the mildly warm to hot range.  This sensing ability may play an important role in the way we respond physiologically to hot temperatures. The building blocks, or subunits, of heat-sensitive ion channels can assemble in many different combinations, yielding new types of channels, each capable of detecting a different temperature. In cell cultures, this demonstrates that only four genes, each encoding one subunit type, can generate dozens of different heat-sensitive channels. Ion channels are pores in cell membranes. Their ability to open and close controls the flow of charged ions, which turns neuron signalling on or off -- in this case to inform the body of the temperature the neuron senses. It says 'I remember this temperature. I will make a really loud noise to tell the system that it is coming.'


A cultural adaptation is the turban. A turban is a piece of cloth wrapped over the head that immensely helps as a barrier between the hot sun and your skin.  Turban styles vary from region to region. The Sikh turbans are simple cloths wound round the head with a prominent front fold above the forehead. Muslim men often wrap turbans around their caps, known as kalansuwa. Afghan men often favor longer turbans that leave a tail hanging down the back. The turbans of Iran are usually black or white and wound flat and round against the top of the head. Indian turbans can be some of the most elaborate, covered with gems, jewels and embroidery. Some of the simplest turbans are those worn by African desert dwellers that swaddle the cloths about their heads and face for protection.


If you take anything away from this, it is to help you remember to keep hydrated so you can keep sweating in hot climates, and that the more you let your body be in these climates, it will be able to sustain itself easier over time and 'practice' so-to-speak.

Human race does not really have an effect on the way a human retains heat. It is some relevancy to study the effects of heat on different people close or further away from the equator, but even this is not trustworthy due to the vast variation of peoples today in different cultures. It is all the individual, so it is much more productive to study the environmental effects on humans rather than race.

Wednesday, March 21, 2012

Language

Part one was difficult, because I had to use my hands to even conceptualize what I'm trying to say. Bold facial expressions are the most help, because it shows them the broad idea of what the thought is coming from. I mostly just tried to illustrate objects and then build on that, sort of like playing charades. The person I was conversing with (my brother) had to resort to easier subjects to converse with. We only really talked about what was around us, if something made us laugh or if something made us angry. If a speaking culture was talking to a culture that didn't use symbolic language, they would think of them very primitively. Being able to speak is the only way to convey complex ideas. People who are mute are dealt with very easily, by either writing down on paper what they want to say or what we want to say, hand gestures, or just tell them if they aren't deaf.

Part two was fairly easy because I could just paint a picture in my brother's mind by describing what I'm trying to get across. It was slightly difficult for my brother and I to not show any emotion and just have a poker face the entire time, but it was easier to lose body language than to lose spoken language. Using signs with our hands and emotion in our faces is definitely important though. With it, it is much easier to both illustrate our ideas and speak about them. Oblivious people can sometimes not pick up on body language, but it is easier to hone it on and understand it when in social situations.

Tuesday, March 6, 2012

Piltdown man hoax

The bones were originally found by Charles Dawson in a gravel pit in Piltdown, East Sussex, England. It consisted of part of a jaw bone and some parts of the cranium. For many years since it's discovery, many scientists were cynical at his validity of actually finding them. Arthur Keith and Smith Woodward were very prestigious and since they were involved, no one really doubted it intensely.

Scientists desperately wanted to know what the missing links between apes and humans were, very passionately. So just by ignorance and goggled observations, the faults in the bones were overlooked. Letting this happen dents the scientific process' trustworthiness as every aspect of observing something that has never been observed before becomes so much a contest that cheaters come about.

Examining the carbon dating of the bones and teeth gave substantial evidence it was a fraud. The skull was a 500 year old Medieval man and the jaw was of an orangutan, with the teeth of a chimp. Also, while under a microscope, it can be seen clearly that someone had filed down the teeth to make them look like they had been chewing side to side.

You can't remove the human factor. Or else why would there be science in the first place? It is the study of our history, so removing 'our' would be a misstep. It takes the human factor to want to find new discoveries if there isn't a piece found in the large puzzle of evolution. If there isn't that want, nothing will be found, and may never be found.

The lesson to take from this hoax is that it happens. Science can be taken very royally and have an 'unwritten' rule that we will take each others word for it that your findings are legitamite, since we are colleagues. But that may sometimes not be the case, and there will be con that invalidates that trust.

Thursday, March 1, 2012

Comparing Primates - Diet


Lemurs (Prosimians/Strepsirhini)

a.    Lemurs are known specifically to Madagascar. It has two different climatic zones, the rainforests of the east the dry regions of the west. With these challenges, along with poor soils, low plant productivity, wide ranges of ecosystem complexity, and a lack of regularly fruiting trees have made their survival the ability to endure the persistent extremes, not yearly averages.
b.      At least 109 of all known plant families in Madagascar (55% of all plants) are exploited by lemurs. Most of these are woody plants, including trees, shrubs, or lianas (woody vines).
c.       By being on an island, lemurs are geographically isolated, so they have no choice of what they need to eat, they eat what is plentiful.



Spider Monkey (New World Monkey/Platyrrhini)

a.       Spider monkeys are frequent in southern North America below Mexico and northwest South America, mostly in tropical forests.
b.      Their diet consists of 90% fruits and nuts. They can live for long periods only eating one or two types of them.
c.       They most likely eat these foods because they spend their time hanging from trees and scanning the forest for something with protein and sugar.


Baboon (Old World Monkey/Cercopithecidae)

a.       Baboons are found throughout Africa. They are split into 5 species, all which inhabit their own section of the continent - papio hamadryas (east), papio papio (west), papio anubis (central), papio cynocephalus (south central), and papio ursinus (south).
b.      Being terrestrial and found in open savannah, open woodland and hills across Africa, their diet is mixed. They are mostly herbivorous but can be omnivorous, they eat insects and occasionally prey fish, hares, birds, other monkeys, and small antelopes. They are also foragers, and can raid human dwellings throughout Africa.
c.       Because most of Africa is open terrain, they have to scavenge whatever food they can, so they aren’t picky. 


Gibbon (Lesser ape/Hylobatidae)

a.       Gibbons can be found in Southeast Asia, their separate species are hylobates (southern China and central west Java), hoolock (extending from northeast India to Myanmar), nomascus (China and southern Vietnam), and symphalangus (Malaysia, Thailand, and Sumatra).
b.      Gibbons thrive on the abundant fruit trees in their tropical range, and are especially fond of figs. They will occasionally supplement their diet with leaves and insects.
c.       Many forests are in China and southeast Asia, just like the spider monkey, they are slender, which means less omnivorous diet.


Chimpanzee (Great ape/Hominidae)

a.       Chimpanzee’s are in central Africa. They have two species – pan troglodytes (western and central Africa) and pan paniscus (central Africa
b.      Just like the baboon, they are foragers, and have a mix of an herbivorous and omnivorous diet, a tremendously varied diet that includes hundreds of known foods.
c.       Again, like the baboons, Africa is an open terrain, so whatever is in front of them and will give them calories, they cannot resist.


      I found that the primates that are in Africa (baboon and chimpanzee) have a more savage and foraging diet than the other primates who live in humid tropical forests (lemur, spider monkey, and gibbon). The later primates are definitely more slender because of their environment also, they need  to swing from branches and vines, so are a lot less bulky than the ground dwelling baboons and chimps.