Human Evolution: The Journey of Human Through Time


Based on: A Theory Evolves How Evolution Really Works and Why It Matters More Than Ever by Thomas Hayden

Today we know that mammals co-existed with dinosaurs, birds evolved form Pterosaurs, and doglike mammals transformed into whales. Although some creationists argue that Man was created by God on the seventh day, fossils show that man’s earliest known ancestor was at least 7 million years old. Even astonishing is the fact that life started from single-celled organisms approximately 4.0 billion years ago.

Our understanding of life and its journey began with Greek philosophers but Darwin (with help from Alfred Russel Wallace) was the first to propose a convincing theory and mechanism of evolution. 

Darwin’s Theory 

Darwin simply stated that all living beings originated from a single ancestor and thus are related. Organisms accumulate mutations over time and those with beneficial mutations have a stronger chance of survival and those with deleterious mutations will die off. Once in a while there will be mutations that will give rise to a more complex organism from a simpler organism and these complex organisms can survive better than the simpler ones thus they fluorish and pass that mutation off to their offspring. Overtime, due to accumulation of many different beneficial mutations, a new organisms arise. Darwin called this process natural selection.

Genetics: What Darwin did not know 

Darwin was not fortunate enough the witness the wonders of modern technology but today, due to genetics, we know that a mutation can give rise to a new species in simply one generation. In addition to genetics, modern day paleontologists, linguists, and anthropologists are using advanced technology to decode the process of evolution–one very interesting area of decoding the past has been discovering human origins.

Natural Catastrophes Have Shaped Evolution 

Advanced science and new discoveries have demonstrated that at different times in history, natural catastrophes have nearly wiped out any signs of life in our planet; for example, the asteroid impact that killed the dinosaurs 65 million years ago. The extinction of dinosaurs allowed mammals to fluorish. Even in recent history, Ice Age and volcano almost wiped out all human forms from Asia and Europe. Numerous species, including humans, have passed through various bottlenecks at different times in their journey as a species. But every time they have survived, they have acquired new traits to become more adaptable to their new environments. Those arboreous apes that were desperately seeking ways for survival in drying Savannah once learnt how to hunt got the vast African plains and its flora and faunas…eventually to give rise to a bipedal human ancestor.

Darwin did not know but what we know 

Evolutionary and Developmental scientists have found that variations in homeotic genes, a handful of key genes that control development, can be enough to drastically reshape an animal.  Homeotic genes are regulatory genes that master switches, proteins that bind to DNA and can either turn on or shut down other genes that make tissues.

Based on these findings, scientists have explained how many legged arthropods gave rise to six-legged insects 400 million years ago, and how the first vertebrate jaw was formed. Scientists have also found that gene duplication, a genetic accident might cause an individual to have two genes one set can carry the normal functions but the other less used set can mount mutation and can be adventurous in the evolutionary front.

Scientists today can explain how expansion of brain sizes of modern humans occured. While large brain size allowed ancient humans to accelerate in the process of evolution, acquired knowledge of tools caused them to thrive in unimaginable conditions. In addition to large brain and tools, humans developed language, a trait unique to humans only, which led to formation of social groups and cultures. Whenever food became scarce, humans migrated out of their territory to conquer newer lands in search of food and eventually reached every corners of the world.  

Clean Cut Design ?

Of course any product of such a trial and error process will not be perfect and no living beings are. As opposed to a clean cut design hypothesis of the creationists, all complex living beings are “a messy legacy of complicated biochemical pathways and body parts that are more serviceable than sleekly designed.” The biochemical and immunological process that ensure our survival and defense against pathogens are not perfect or simple. They are a chain of reactions involving various components and processes.

The process of evolution is not over for us yet. Resistance to infectious diseases, suseptibility to pathogens, mutations that cause severe development disfunctions…these are some of the evolutionary processes we are still dealing with. “We continue to accumulate mutations,” says Sarah Tishkoff, a geneticist at the University of Maryland. “But we’re altering evolution.” Assisted reproduction allows some people to beat natural selection, she notes, while birth control gives an evolutionary leg up to those who don’t use it.

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