Tuesday, November 20, 2012

The Piltdown Phony



         The Piltdown Man hoax all began in the small village of Piltdown in England. The discovery of these fossils was made in the early 1900's by a laborer. The find was then handed over to an amateur archaeologist by the name of Charles Dawson. Dawson had concluded that this was an amazing find, a probable early ancestor to humans. The earliest one ever found. Dawson took his find Sir Arthur Smith Woodward a geologist at the Natural History Museum in London. The two men had claimed the Piltdown Man to be the earliest human ancestor. The age of the fossil was presumed to be half a million years old. The Piltdown Man became more of a sensation that a scientific discovery. 
          In 1949 a new method for roughly estimating the age of fossils was discovered. This new method measured the fluorine content of fossils. The Piltdown Man was estimated at that point to be 100,000 years old. This would mean that the fossil was a lot younger than originally thought. In 1953 there was a full-scale analysis done on the Piltdown Man and it was discovered to be a hoax. The revelation of the hoax was an embarrassment for scientists had spent their careers analyzing and claiming the fossil as genuine. The British scientific community faced the biggest embarrassment. Other scientists had already begun to doubt the authenticity of the Piltdown Man. 
          There were many things that went wrong with the acceptance of the Piltdown Man. Arrogance would be the biggest human fault at play in this case. The Natural History Museum of London was very protective of fossil finds. Very few people were allowed access to them. This action didn't allow for a lot of peer review so there was a low chance of discovering the truth. 
          Several dating techniques and analysis helped to prove that the Piltdown fossils were a hoax. The fluoride absorption test was the first in proving that the fossils were a lot younger than originally thought. Later in 1953 the carbon-14 dating technique proved that the fossil was a complete hoax. The carbon-14 dating technique is much more accurate than the fluoride absorption technique. Carbon-14 dating uses the half-life of carbon-14 (5,700 years) and is then compared to the amount of carbon-12 which remains constant since death. Deeper analysis of the fossils also proved that they were a hoax. The jaw bone was discovered to have come from an orangutan and several of the teeth were filed down. The fossils were also found to have been covered in stain to make them appear older. 
          It is not entirely possible to remove the human factor from science. There will be mistakes and a willingness to accept that which wants to be believed. Several precautions are taken to lower human error. Recording data, using the same instruments, peer-review and other things are used to reduce human error. I would not want to take out the human factor from science. We are curious beings and we want to know what's out there, how it works, and why it does. If the human factor was removed it would no longer be called science. Humans make errors and others "fix" and improve past discoveries. If there was nothing to fix or correct science would no longer be fun. 
         The biggest lesson to take from this event is to stop being so gullible. The scientific community was so eager to find that missing link that they took the first thing offered to them without any questions. Another lesson should go for scientific institutions. They should allow their peers to take a look into their collections to further credit the authenticity or find another hoax. 























Wednesday, November 14, 2012

Body Size and Sexual Dimorphism In Primates

Lemurs (Prosimians/Strepsirhini)
           Lemurs are found off the east coast of Africa including Madagascar and adjacent islands. Most lemur species are arboreal and enjoy a variety of foods. These include leaves, buds, shoots, fruits, and bark. The mouse lemur is omnivorous enjoying frog eggs and insects as well.

           Most lemur species lack sexual dimorphism. When there is dimorphism among a species the female is usually larger. These primates are different from other primates because their social structure is female dominated. Body size varies greatly within lemurs; some species are slightly larger than mice and others are up to four feet long.

           Body size is an adaptation to a lemurs environment. A larger lemur needs less energy to maintain their basic metabolic rate than a smaller lemur would. Their diets show that this is correct because larger lemur species are herbivorous while the small dwarf and mouse lemurs depend on an insectivorous diet.


Spider Monkey (New World Monkey/Platyrrhini)
           The spider monkey is the definition of arboreal they even have prehensile tails well adapted for tree life. They can be found in Central and South America in tropical rain forests.

           The New World Monkeys range between a variety of sizes some as small as 14 cm up to 70 cm. Sexual dimorphism is at a lower degree than the Old World Monkeys and apes. This means that their a hardly any differences between their genders.
 
           The lack of sexual dimorphism helps in the case of New World Monkeys. Males and females are to a certain level equally fit and can take excellent care of their off spring. This probably came about because both genders are involved in child rearing and their is no domination over females. The males do not need to larger and stronger to attract females or fend off other males.


Baboon (Old World Monkey/Cercopithecidae)
           The Old World Monkeys range from arboreal species to fully terrestrial species. They are found in Africa and Asia inhabiting rain forests, savannas, and mountains.

           The smallest of the Old World Monkeys is the talapoin measuring 35 cm. The largest of the monkeys is the mandrill measuring over 70 cm. Sexual dimorphism is very apparent in the Old World Monkeys. Males are significantly larger than females and are dominant. Baboon males have canines up to 4 times the size of a females canines.

            The Old World Monkeys have adapted to their environment to be a certain way. Males have to be stronger and larger than females so that they can mating priority with several females. These monkeys also need to be able to fend off other males who try to copulate with the alphas females.


Gibbon (Lesser ape/Hylobatidae)
           Gibbons inhabit tropical and subtropical rain forests of eastern Asia from northern India to southern China. Gibbons are not considered to be actual apes nor are they monkeys. They are called lesser apes because they have characteristics that differ from monkeys and apes.

           Gibbons measure about 90 cm and weigh 7 kg males and females are fairly similar in measurements. Very little sexual dimorphism is present among gibbons. Males are only slightly larger than females. Males have louder calls than females and use this to attract mates.
           
            As with most species the call of the gibbons is also used to warn others about predators. Their calls are also used to attract mates so males have no need to be larger than females.



Chimpanzee (Great ape/Hominidae)
           Chimpanzees can be found in the rain forests and wet savannas of central Africa.They are both arboreal and terrestrial with an omnivorous diet. The amount of time spent on the ground or in the trees varies greatly depending on the sex.
         
           Chimpanzee exhibit a moderate amount of sexual dimorphism. Males measure up to 1.2 meters and 60 kg, while females measure up to 1 meter and 47 kg. They live in groups with an average of 10 chimps with an alpha male.

            The larger size of the male enables them to become an alpha male and pass on their genes. Males do not need to worry about taking care of their off spring so they are merely sperm donors. They need to be much larger to attract females and fight off other males.




             New World Monkeys have a lower degree of sexual dimorphism than do Old World Monkeys. This was also noted in gibbons and lemurs. Chimpanzees and the Old World Monkeys exhibit a greater deal of sexual dimorphism. Some of the groups had dimorphism similar to that of humans.

             The groups that had very little or no sexual dimorphism tended to have more parental care. Meaning that both males and females took equal part in taking care of the offspring. The lack of sexual dimorphism may have to do with the behavior of each groups. Males are in less competition with each other because they exhibit what we would call monogamy.

             Groups that had alpha males or were mainly male dominated had greater degrees of sexual dimorphism. The males in these communities have to be stronger and larger than other males to be able to pass on their genes. Males are in direct competition with each other so their bodies need to be adapted to fight.













Thursday, November 8, 2012

Homologies analogies I don't gerr it.

Two homologous species: 
             Let's try a clouded leopard and a cheetah. Both of these species have claws but the claws provide different uses. A cheetah is known for being a fast runner and reside in Africa and Southwestern Asia. The clouded leopard is more arboreal. Their main habitat is in tropical and sub-tropical evergreens near Bangladesh and Thailand. 
             The cheetah and the clouded leopard both use their claws for hunting prey. Their claws also provide a different use. A cheetah uses its claws to help it run. The claws help them accelerate and make sharp turns at high speeds. The clouded leopards claws help the cat live and hunt among trees. This cat is not afraid to get down from trees. Their claws dig into tree bark and are specially designed to help the animal climb up and down with agility. Both species are from the family felidae. 

            I am sure that the common ancestor to both of these species had the same trait. Both the claws of the leopard and the cheetah are used for hunting. So I would assume that this is one of the traits inherited by the common ancestor. 


Two analogous species:
              How about a kangaroo and a grasshopper. The grasshopper dwells in grass leaves and some eat from many plants. They also need to be able to escape predators. Their legs provide that function allowing them to jump really high.

              A kangaroo one of the most famous marsupials is endemic to Australia and New Guinea. kangaroos have very few predators but they still need to be able to escape. Their huge legs allows them to hop as fast as 40 MPH for a large distance as well. Their legs are very efficient mainly because the hopping action allows them to inhale large amounts of air. 

             They both have pretty strong rear legs the envy of the animal kingdom. A grass hopper uses their legs mainly to jump but they also need to be able to take a few steps instead of leaps. Their legs consist of a femur and a tibia. 

              A kangaroo uses it's big legs to reach great speeds without using a lot of energy. A kangaroo's tendons act like a rubber band and help the animal propel forward. The kangaroo also has huge feet to stabilize its huge powerful legs. 
              
               I don't think that the common ancestor of the two species shared this trait. The legs for both species serve the same function but their ancestral lines diverged a very long time ago. 

Thursday, November 1, 2012