Everyday we use our hands to do all sorts of task. One of the most important features of our hands is that thing we call a thumb. With the help of having thumbs it has helped humans develop better motor skills. Imagine without our thumbs the things we couldn’t do. Would have our ancestors even developed tools? Would we even be considered as advanced as we are now? Most likely no humans would be.  But how did this opposable thing become on our hand become and are there other creatures with similar appendages?

  When it comes to looking at the evolution of the thumb it is seen with in Homo erectus or Homo habilis. What cause the thumb to become advanced though in our ancestors? A possible idea is the advancement of walking up right as proposed by Suzanna Kemmer. It is thought that as our ancestors began to walk up right there was now new usage for their hands. From this they created tools and learned to use resources that were around. Another possibility is the development of a gene enhancer known as HACNS1 that was found by Yale scientist. The HACNS1 enhancer is thought of as being a “human-specific gene enhancers, which are switches near genes in the human genome.”
 
  Knowing the possibility of our thumb makes us wonder how certain other animals developed their own thumbs. Primates have four categories that divide them based upon their thumbs. There are non-opposable, pseudo-opposable, opposable and opposable long. What causes their classification of thumbs different from ours is the fact that their thumbs do not fully rotate along its axis like our own does. So categories are divided by the amount of independence the thumb has. Other animals with “thumbs” are Giant Pandas (not a actual thumb but a extra bone that functions as one to help them eat bamboo), certain marsupials (in order to climb and gather food) and most birds also have an opposable digit.
 
  Without the thumb or in the case of other animals with thumb like appendages where would they be? Where would we be? Better yet one should ponder with this special adaptation we have what could possible evolve next from it as an adaptation. Will our thumbs slowly change in shape, size or movement? Or will that happen to another species? Who is to actually say what will happen. All we can do is watch what will take place.


Sources:
http://www.primates.com/faq/index.html
http://books.google.com/books?id=5fttVRAHA4MC&pg=PR11&dq=Ankel-Simons,+Friderun+(2007).+Primate+Anatomy+(3rd+ed.).&hl=en&ei=F4zcTNuyKoL78Aaw9JjrCQ&sa=X&oi=book_result&ct=result&resnum=1&ved=0CDEQ6AEwAA#v=onepage&q=nonopposable%20thumb&f=false
http://www.molecularstation.com/science-news/2008/09/junk-dna-hacns1-discovery/
http://onlinelibrary.wiley.com/doi/10.1002/ajpa.1330150203/abstract
http://www.ruf.rice.edu/~kemmer/Evol/opposablethumb.html

The Hanuman Langur is an Asian monkey; whose social behavior is uncanny. Their troops consist of both males and females numbering around 125. The head male—of a troop where there is one male—is competing with other males to maintain his position as leader. When a group of males overthrow the leader —so to speak—they kill his offspring. After that “ritual” one male becomes they new leader. That male then mates with the females of the troop and the process is repeated. The males gain a reproductive advantage because the females are at their maximum sexual receptivity when they lose their offspring.

·      This species is vulnerable to infanticide.

·      Males attack the infants only if they were not present at the time of contraception.

·      The males are usually protective of their offspring, however some still kill their own young.

 Ecology, Social Structure & Evolution

·      Ecology pressures that influence sex ratio populations also affect group size and social structure.

·      Increasing the Hanuman Langur troop size might prevent takeover and infanticide.

 One study reports that species such as:  P.ursinus, Propithecus diadema, and Semnopithecus entellus (Hanuman Langur) have over a 10 percent mortality rate of infants. Another species, the Red Howler species, shows that the rate of infanticide increases with group size. However, there was a change in rate when the Red Howler groups became large enough to cause paternal confusion—the males in the species normally do not kill their own young. The confusion causes males refrain from infanticide, which causes an overall decrease in the infanticide rate.

Because the social behavior of the Hanuman Langur depends on ecology...ecological evolution impacts the behavior. The ecology of the Hanuman Langur includes varied troop sizes and varied troop constituents, which evoke different behaviors. As previously stated, troop size impacts the level of infanticide.

Questions for Research

What does the social behavior of hanuman langur imply about evolutionary desires to be a leader or at an advantage by any means?

What does this behavior say about evolution in general?

Hanuman Langur selectivity and evolution…

Sources

www.eva.mpg.de/ipse/pdfs/Ostner_etal2006.pdf

http://chapmanresearch.mcgill.ca/publications.html

http://www.theprimata.com/semnopithecus_entellus.html

http://www.cabrillo.edu/~crsmith/hanumanlangurs.html           

 

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Question: How do diseases in animals and diseases in humans show the different evolutionary paths that we have gone down and what does it say about our immune systems?

Animals and humans can get the same diseases but to my knowledge there are some diseases that we are immune to that they aren't and vice versa. Humans have had an advantage for the past century or so with having plumbing access to for the most part clean water and other means to prevent and fight diseases. Penicillin and amoxicillin are among pills that are made to fight and prevent diseases. Animals on the other hand have evolved in the wild where they have to rely on natural selection and how they have evolved to adapt in their environments to fight off sickness and disease.

Zoonotic diseases are diseases naturally able to transfer from animals to humans and vice versa. This shows that we share some of the same immune system capabilities as animals. For instance it is known that while sharks are able to get cancer their immune system prevents cancer/tumors from being able to grow.The recent Swine Flu outbreak is recent evidence of this resulting in many people becoming ill and around 12,000 actual deaths in the U.S. in the recent 2009-2010 outbreaks, and shows how diseases originate in animals and transfer to humans. AIDS however is a disease that cannot from my knowledge and research thus far, be contracted by animals except for in chimps. Is this because of our DNA similarities and because of the similar evolutionary path that we have gone down? Also, how has the evolutionary path of diseases influence how and who it effects between animals and humans? What about the sharks? Has evolving in the ocean over these millions of years gave them a sort of advantage from not letting cancer or tumors progress?

These following links show other diseases and how either vaccines are similar or animals and humans can contract similar diseases.

http://news.bbc.co.uk/2/hi/health/7270562.stm

http://www.mrmcmed.org/aids.html

http://biology.clc.uc.edu/courses/bio105/immune.htm

http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=imm&part=A1480

http://www.nature.com/nature/journal/v248/n5446/abs/248344a0.html

http://www.elasmo-research.org/education/topics/p_bite_on_cancer.htm

http://pin.primate.wisc.edu/aboutp/pets/zoonoses.html