Comparative Primate Blog Post: Dentition Patterns

Environment

Lemurs are indigenous to Madacascar, off the southeast coast of Africa. Madacascar is 1650 km long and is divided into two parts by a mountain chain that runs north to south. Each side of the mountain chain has a different climate, topography and vegetation. The southeastern portion of the island ranges from sea level to 8530 ft. and is full of various forests and rain forests. The southwestern part of the island gets very little rainfall and is primarily desert. Winter typically lasts from May to September and summer from December to March.

Spider monkeys reside in tropical rainforests typically located in Central and South America (some even being found to live as far north as Mexico). They reside in tree tops or “upper canopy” of trees and very rarely come down to ground level.

Baboons live in Africa or Arabia. They prefer savanna and other semi-arid habitats. Some baboons can be found in moist evergreen forests but the majority of baboons can be found living in open woodlands, grasslands and rocky hill country ranging from sea level to 2600 meters.

Gibbons prefer to live in tropical and subtropical rainforests. They can be found from northeast India to Indonesia and north to southern China. Gibbons are another of the tree dwelling primates, living only in the moist wetlands of southeast Asia.

Because Chimpanzee’s are easily adaptable they can be found throughout Africa. Their natural habitat is the rainforest, however, they also dwell in the savannas, woodlands, and bamboo forests.

Dentition Patterns

Lemurs have unusually rapid dental development and have a tooth pattern of 2-1-3-3. The toothcomb of a lemur normally consists of six teeth (four incisors and two canines). By the time Lemurs are weaned, they have acquired their full permanent teeth. They have thin tooth enamel compared to other primates which may cause premature tooth decay and loss.

Spider Monkeys have large incisors and small molars with low rounded cusps. They also have a tooth pattern of 2-1-3-3.

Baboons have heavy, powerful jaws with sharp canine teeth. Their tooth pattern is 2-1-2-3. Their canines can grow as long as two inches and are often used by the male of the species for intimidation.

Gibbons have teeth similar to great apes with rounded cusps and large canines in the upper and lower jaw. They have a tooth pattern of 2-1-2-3.

 

Chimpanzee’s have a 2-1-2-3 tooth pattern and are characterized by having large canines.

All five of these primates use their teeth for being able to bite into and chew their diets of fruit, grass, bark, and in some cases, small insects. In the case of baboons, gibbons and chimpanzees, their teeth are also used for intimidation against others of their kind. Being as all of the above mentioned primates are tree dwelling at least half the time (up to and including exclusively) it would only stand to reason that that the dentition of these animals would need to be capable of being able to ingest anything found in the trees in which they reside.

Analogy / Homology

1.       Homologous trait:  Opposable thumb

a.       The most anatomically modern humans, also known as homo-sapiens, have been around for roughly 200,000 years and are said to have originated in Africa. They are known for their highly developed brain, ability to reason, problem solving skills and language capabilities. These, along with their skeletal structure, physical make up, ability to walk upright, and opposable thumbs are what distinguish humans from any other species on Earth.

Orangutans are primates that are from the great ape family. They are known as being among the most intelligent primates and typically have longer arms than other great apes. Orangutans are native to Indonesia and Malaysia.

b.      An opposable thumb can be placed opposite the fingers of the same hand and allow                     the digits to grasp and handle objects. The usage of opposable thumbs in one difference between the human and the orangutan. Humans use their hands and thumbs for grasping and manipulating objects while Orangutans, who also use their thumbs for these purposes, also use their hands to walk. Another importance difference that separates the two thumbs is length. No other primate has a thumb that is as long as a humans thereby not being as productive as the human thumb.

c.       Both humans and the orangutan originate from the Hominidae Family. Hominidae has three branches: gorillas, chimpanzees and humans. Only recently, within the last 30 years, has this family included gorillas and chimpanzees.

2.       Analogous trait:  Front pouch

a.       A kangaroo is a marsupial that is native to Australia. They are known for having large, powerful hind legs, large feet (for leaping), a long muscular tail (for balance), and a small head. Their only means of travel is through hopping and they are strict herbivores. One well known characteristic of the female kangaroo is her marsupium, or pouch, where she will keep her joey until it is ready to leave, which is usually about nine months.

Seahorses are fish that range in size from .6 inches to 14 inches long. They do not have scales but rather a thin skin that covers the surface of their bone structure. They are found throughout the world and are known for their distinctive body shape, which gives them their name. They are among the only species in the world that is given birth to by the male of the species.

b.      Despite their differences, the kangaroo and the seahorse both use pouches (known as the marsupium in kangaroos and brood pouch in seahorses) to “give birth to”  and develop their young.

c.       Honestly, I have no idea who their common ancestor would be.

Protein Synthesis

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Jean-Baptiste Lamarck

Jean-Baptiste Lamarck (1744-1829) never quite received acceptance for his ideas on evolution. Yet despite his theory of heredity being discredited, Charles Darwin himself was actually quoted as saying:

“Lamarck was the first man whose conclusions on the subject excited much attention. This justly celebrated naturalist first published his views in 1801. . . he first did the eminent service of arousing attention to the probability of all changes in the organic, as well as in the inorganic world, being the result of law, and not of miraculous interposition.”

As a professor at the Musée National d'Histoire Naturelle (National Museum of Natural History), Lamarck continued his studies regarding evolution and in 1809 published Philosophie Zoologique. His work focused on two specific laws; that the use or disuse of specific features and attributes on an organism would cause them to enlarge, shrink or even disappear (also known as the use-disuse theory), and that traits acquired during a single lifetime could be inherited, which we now know to be false.


Lamarck believed that throughout an organism’s lifetime, changes would be made to acclimate to its surrounding environment. In turn those adaptations would be passed on to each subsequent generation. He also felt that evolution was a “process of increasing complexity and perfection”. For Lamarck, species did not become extinct and disappear - they simply evolved into different species. 


Source: http://www.ucmp.berkeley.edu/history/lamarck.html

How Does Evolution Work?

·         Individuals do not evolve. Populations do.

The most striking difference between Darwin and Lamarck’s theory of evolution was the concept of inherited traits. Lamarck incorrectly believed that a species could alter its own attributes during its lifetime and pass that “new and improved” trait on to its offspring. Darwin realized this faulty way of thinking and was able to expand on this idea with his concept of Natural Selection.

4.  Darwin may have eventually come up with his theories of evolution and natural selection without the teachings of Lamarck. Especially with others such as Georges Cuvier, Charles Lyell, Thomas Malthus, and Alfred Russel Wallace all contributing to this field of science. However, Darwin himself, credits Lamark as being a great zoologist and forerunner in evolution. There is no doubt, that despite their different conclusions, Lamarck had great influence over Darwin’s work and eventual accomplishments.

5.  Naturally, On the Origin of Species was seen as an affront to the church and its beliefs. To go against everything the church stood for was not something to be taken lightly and was of great concern to not only Darwin, but to friends and colleagues, as well. Yet, the controversy surrounding the publication of such a radical book was not enough to keep Darwin from keeping his findings out of the public view.