Proof that my dog is part of the family!

1.  I love my dog, Petey, and so it was a great surprise to find out that we have homogolous traits linked to a recent common ancestor.  The most obvious is our forelimb, which on me is my human arm and on Petey is his front leg. Now, even though Petey loves to smack me in the face with his "arm" when I stop petting him, his forelimb is quite different than mine because it is developed so that he can walk on all fours, with the upper bone curving back, and the "finger" bones bending forward to support his weight and help with balance. My arm has an opposable thumb, hangs straight, and is perfectly suited to pet my sweet doggie for hours! While both Petey and I are members of the Anamalia Kingdom, it is our subphylum, Vertebrata, which accounts for the emergence of our shared forelimb trait.  I believe this would be where our most common ancestor might be found, although we are both members of the Mammalia class, and are also in the subclass of Eutheria which is placentials.

2. Both the dolphin and the herring, predators in the water, have streamlined bodies with a dorsal fin on top which helps them survive and thrive as they search for food in the water.  However, these are analogous traits because while the herring is a species of Osteichthyes (bony fish), the dolphin is a mammal from the Cetecea order. Dolphins are actually mammalian carnivores which eat fish.  If we look back in the ancestry tree we can see that both the dolphin and the herring are vertebrates, which would be where they share the vertebral column which eventually developed into their streamlined bodies and top fins, but there does not seem to be a shared ancestor possessing the specific traits of streamlined body and top fin (although other Osteichtyes have these traits).  Other species in the Dolphin's Cetacea class are the porpoises and whales and neither of these species possess both the streamlined bodies and top dorsal fin (porpoises have the fin but are not streamlined) of the dolphin. This is perhaps because it was unnecessary until it evolved independently as a means of survival for these two species who needed to moved quickly and turn adeptly to ward of predators and find food.

Protein Synthesis Blog

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 I believe that Thomas Malthus had the greatest influence over Charles Darwin’s development of the theory of Natural Selection.  In An Essay on the Principle of Population , Malthus wrote “Population, when unchecked, increases in a geometrical ratio. Subsistence increases only in an arithmetical ratio. A slight acquaintance with numbers will shew the immensity of the first power in comparison of the second. By that law of our nature which makes food necessary to the life of man, the effects of these two unequal powers must be kept equal.” (http://communitybooks.ebooklibrary.org/members/blackmask_online/popu.pdf, )

Malthus’ essay on population control being driven by availability of resources and ability to acquire them is the foundation of “survival of the fittest” .  In particular, his point that resources are limited.  As our book points out, after Darwin read Malthus’ essay he was able to explain how new species came about.  Malthus shed light on the fact that populations grew faster than resources could accommodate and this led Darwin to reflect upon the nonhuman population, which seems to be naturally regulated by supply of limited resources and ability to acquire them.  This, in turn led him to consider the constant struggle for survival that must occur as a result of this phenomenon, and that struggle is the very essence of natural selection because it is the impetus for being or becoming the fittest, or having the greatest reproductive success.  I believe that Darwin probably would have gotten to this eventuality without Malthus, but it possibly would have taken longer and, because Alfred Russell Wallace was nipping at Darwin’s heals in discovering and publishing the keys to evolution, had it not been for Malthus we may have all learned Wallace’s Theory of Evolution.

It took Charles Darwin over 20 years to publish On the Origin of Species. When it came to the origin of mankind, the prevailing belief of the day was a literal translation of the creation story in the Book of Genesis in the Bible.  Darwin, who had actually studied theology at Cambridge, was at risk of losing his position in society, and even within some circles of the scientific community by publishing his findings which were at such odds with the majority opinion of the day.  Fortunately, with science on his side, he had the courage to go against the norm, and in doing so forever changed the ‘norm’ with regard to evolutionary theory.