Week 5
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Evolution Transition

Chin Chun Ming

003F11713

Evolutionary Psychology

Introduction

Evolution is a change in population on Earth. It can happen in large major groups of living things, or as well occur in minority species. Since Earth was formed 4.54 billion years ago, living things started to emerge and grow. Nowadays, living things from a single unicellular organism already developed into million types of various species. All of these changes are positive and essential for living things to survive. Yet, throughout these changes and evolution process, there were many of the living things fail to adapt and eventually extinct. The reason behind these failures is mainly caused by drastic changes in environment, weather, and geological features.

Earth has been through many stages within these 4.54 billion years. In different stages of Earth, the geological features and condition are different too. There were four eras which are Hadean, Archean, Proterozoic and Phanerozoic era. Each era has different geographical condition, which was highly influence towards living things on Earth. For example, the temperature on Earth during Hadean era was too high due to frequent volcanism and outer asteroids collision. Proterozoic era Earth was covered in ice, with very low temperature.

According to evolutionary theory, humans did not appear as human on Earth “suddenly”. Humans evolved from another type of organism throughout billions of years. In the same time, other organisms nowadays such as cat, dog, dolphin, and monkey also evolved from same ancestor billion years ago. According to Darwin (1859), all species evolved from the same ancestor during Archean era of Earth, which are the protozoa. From protozoa to humans, there were many transitions happened and this paper is focusing on those evolution transition topics.

Transition of Earth

To describe Earth in an easy way, Earth is just like a rental house. At first there was tenants lived in there, after a while the old tenants moved out and new tenants moved in. The reasons why they moved out maybe because of the weather is too hot, the air conditioner is not cold enough, or the environment is not suitable. Similar to Earth, the transition happened on Earth might provide a good environment for some organisms to live but also sometimes provide bad environment which caused most organisms faced extinction. To get a deeper view in it, we need to understand the stages that the Earth had undergone and events that happened during that time.

1) Hadean eon

According to University of California Museum of Paleontology (2011), Hadean eon (4.6 to 4 billion years ago) was the early formation of the Solar System. The sun appeared as a cloud of gas and space dust, attracting and compressing into one giant gas ball and started to undergo nuclear fusion. As a result of nuclear fusion, massive amount of heat was released. At the same time, space particles around the sun started to merge by gravity into planets and smaller particles united into asteroids and comets.

Once Earth was formed, the core emitted very high amount of heat energy and the surface of the Earth is in molten rock state. This stage is known as Hadean era. During Hadean era, the condition of the Earth is under very high temperature and there was no breathable air. Hadean era lasted for 2 million years and throughout the years uncountable volcanism and asteroid collision has happened. These harsh conditions and phenomenon could not allow any organism to live on Earth. Thermophilic organisms (organisms that preferably live in high temperature environment) might have originated in this period, yet the temperature range favored by thermophilic organisms did not appear for most of the history of the Earth (Pace, 1991). This statement leaves several hypotheses that life did not start at Hadean eon.

During early 4.4 billion years ago, the Earth started to cool down and the water vapor started to condense into liquid. According to an extraction activity in 2014, a fragment of zircon crystal has been discovered in Jack Hills, Australia. Zircons have highly resistant towards chemical changes just like gold, also shows that the zircon crystals crystallized 4.4 billion years ago. This statement reinforce that 4.4 billion years ago the Earth had started to cool down and water was present during that time. Besides from water, there were several important elements and compounds appeared abundantly in the atmosphere such as nitrogen, nitrogen oxide, carbon dioxide, methane, ammonia, hydrogen and hydrogen sulfide (Zamora, 2014). Amino acids are the first organic molecules to exist on the Earth. As the structuring of proteins, amino acids are the basic unit of it and linked to almost every single life on Earth which consists of protein. According to Nature Education (2010), amino acids appeared between 4 billion and 3.5 billion years ago in Hadean eon through chemical synthesis of ammonia, hydrogen, methane, and water vapor. Because of existence of amino acid, single-stranded protein which is ribonucleic acid (RNA) had developed and later on developed into deoxyribonucleic acid (DNA). It was the first genetic material exists on Earth and also known as the beginning of life. The first life form is known as protobionts.

2) Archaean eon and Proterozoic eon

During 3.9 to 3.5 billion years ago, the Earth had entered a new eon, which was the Archaean eon. Protobiont organisms had developed into a more complicated organism called prokaryotes. Prokaryotes have the ability to undergo asexual reproduction, which is binary fission to divide themselves into two offspring (Bult,et al, 1996). By using this reproduction method, the ocean of the Earth was full with prokaryotic organisms during Archaean eon. A very amazing phenomenon was happened during this time which was the level of oxygen in the atmosphere shot up from none to 10%. This phenomenon was happened because of the development of a new prokaryote called cyanobacteria. Cyanobacteria have the ability to make food through photosynthesis, which is the process by taking in carbon dioxide gas and release oxygen gas (Kendall, et al, 2010).

During 3.5 to 2.1 billion years ago, a new type of organism had emerged which is the eukaryote. Eukaryote can be comprehended as the “ancestor” of all plant and animal. Eukaryotes developed a digestion process called endosymbiosis, which means one eukaryote will parasitize another eukaryote and become a more complex organism. As the endosymbiosis process continues, the eukaryote become more complex and eventually develop several organelles in one single cell and possess different function in each of them (Bult,et al, 1996). By 1.5 billion years ago, multicellular organisms grew abundantly according to fossil record. According to Smithsonian National Museum of Natural History (2007), the oldest known multicellular eukaryote is Grypania spiralis, a coil and ribbon-like fossil was found in Michigan. The dating system shows that the eukaryote fossil was formed 2.1 billion years ago. Thanks to evolution of multicellular organism, sexual reproduction ability was developed to replace asexual reproduction. Sexual reproduction is very important because it can induce variation among organisms and variation is essential for evolutionary process.

3) Phanerozoic eon

a. Cambrian Explosion

Phanerozoic eon is the last eon and also the current eon that we are living under. 535 million years ago, eukaryotic organisms began to bloom rampantly. This phenomenon is known as Cambrian explosion. For 10 million years, aquatic animals evolved most of the elementary body forms like nowadays worms, starfish, crustaceans, algae, and sponges (Wang, et al, 1999). Also in Cambrian period, prey-predatory became more vicious and multicellular organism started to use seawater and mineral to build up “weapons” such as claws, and prey built up defensive “shield” such as hard plates and shell.

b. Ordovician period and Devonian period

At Phanerozoic eon’s period, Ordovician period approximately 505 to 540 million years ago was the period where animals and plants started to colonize together to avoid predation. Until 365 million years ago, it was the Devonian period. At Devonian period, there were two major dominant species living on the Earth, which were the tetrapods (animals with four limbs) dominating the land and brachiopods (animals with two hard shells located top and bottom) dominating the ocean (Speer, 1998). Animals started to live on land since there was a formation of land masses in this period. During Devonian period, there were three major continent masses which were Paleosiberia (a portion of modern Siberia), Euramerica (combination of modern North America and Europe), and Gondwana (combination of South America, Africa, Antarctica, India, and Australia). There was no mammal, reptile, or amphibian organism developed in this period, only fish-like organisms. Besides, plants also began to spread on the land in very small amount and sizes. Those plants did not have roots or stem and did not grew more than few centimeter tall. But then, during late Devonian period plants started to increase in population and started to grow roots and leaves.

c. Carboniferous period

In 399 to 259 million years ago, the Earth stepped into a period known as Carboniferous period, the Coal age. The increasing of animals caused the amount of carbon dioxide increase, which was extremely favorable by plants, as a result causing plants to grow rampantly on land. As population of plants increases, the photosynthesis process (process which plants make food by taking in carbon dioxide and releasing oxygen under sunlight) became much more frequent. In a very long geological time, the oxygen level in the atmosphere was too high and reached 35% portion of air. According to National Geographic Society (2014), insects and spiders grew in massive size due to high amount of oxygen in the air. Centipedes can grow into maximum size of 2 meter long and dragonflies can develop into 0.75 meter long. After over several million years, the climate started to change and the amount of carbon dioxide in the atmosphere was harshly decreasing due to excess growth of plants. The declination of carbon dioxide caused the collapse of whole carboniferous forests kingdom and those remains of dead trees buried under the land. Nowadays, those remains have become very precious energy resources like coals and petroleum because of the thermal pressure. Also, the collapse of carboniferous forest caused the formation of wetlands, marsh, and swamps, which lead to evolution of reptiles and amphibian. Reptiles and amphibian started to live on land and ocean through wetlands, which allow them to adapt both environments. Amphibians in carboniferous period grew in large size and developed amniote egg reproduction (National Geography Society, 2014).

d. Permian period

In between 299 to 251 million years ago, the Earth stepped into Permian period. During the Permian, a single supercontinent was formed by combining all land masses from all over the world. The supercontinent called Pangaea meanwhile the combination of land masses left a large single ocean called Panthalassa (Kazlev, 2012). The combination of continents encouraged more organisms to start living on the land. Non-flowering plants such as pines, conifers, and ferns became more prominence in this period. Besides, two types of animal roaming widely on the land which was Pelycosaurs (quadruped reptiles with large hard fin on the back) and Archosaurs (the ancestor of dinosaurs and modern reptiles). At the same time, giant carboniferous insects met their extinction due to collapse of carboniferous ecosystem (Kazlev, 2012).

e. Permian Extinction

According to Hoffman (2014), there was a huge extinction event happened even before evolution of mammals and dinosaurs. During 252 million years ago, one of the huge extinction event of species happened on Earth, Permian-Triassic extinction as we know nowadays. Some unknown reason caused 90% of species on the planet met extinction. Only less than 5% of organism lived in the ocean survive the extinction event meanwhile almost all plants died. The speculation for the major extinction event is most probably caused by acid rain, yet there are still many mysteries remain unsolved (Chu, 2013).

f. Triassic period

According to Smithsonian National Museum of Natural History (2007), the end of Permian extinction was recovered slowly during the Triassic period (252 to 201 million years ago). Brachiopods (two shells organism) went fully extinct. But then, dinosaurs started to evolve and began to roam the land. Archosaurs evolved into much diversity of dinosaurs and modern lizards meanwhile a new species called lystrosaurus had evolved. Lystrosaurus was believed to be the ancestor of mammals and it had features similar to pigs nowadays. According to Newitz (2013), lystrosaurus in Triassic period did not have any natural predators who fed on them meanwhile lystrosaurus was herbivore by the way. Besides, they had no sharp teeth or tusk as defense mechanism. Yet, lystrosaurus had strong adaptation abilities toward weather and environment. That is the reason why mammals can survive from the major extinction.

g. Jurassic period

Until 199 to 145 million years ago, dinosaur became the dominant species on Earth in this period, which known as Jurassic period. The name “Jurassic” is referring to the Jura Mountains by Buch in 1839. The domination of huge and giant dinosaur on the Earth threatened mammals’ life and mammals had to grow in smaller size to maintain population (Department of Paleobiology, 2007). In the oceans, plenty types of sharks and marine crocodiles evolved and grew in large number of population. On the land, the first flying vertebrae animal was pterosaur, which evolved to giant bird during late Jurassic period. In Jurassic period, dinosaurs dominated the animal kingdom meanwhile ferns and conifers dominated the plant kingdom. From the geological perspective, Pangaea had separated and some low ground area flooded by sea water. This continental drift caused North America drifted apart from South America and Africa, also formed Atlantic Ocean in between those two continents (Department of Paleobiology, 2007).

h. Cretaceous period

During 146 to 65.5 million years ago, Earth undergone changes in geological and living organism. According to University of California Museum of Paleontology (1995), cretaceous period was the period whereby many types of new diversity appeared. For example, here comes the first appearance of flowering plants and angiosperm, butterflies, and bees. The presence of bees and butterflies encouraged the increasing population of flowering plants because those insects acted as the vector to transport pollen grains for reproduction.

i. Cretaceous extinction

In late Cretaceous period (65 million years ago), dinosaurs who dominating the Earth for several periods met their extinction. Although this Cretaceous-tertiary extinction was not as critical as Permian-Triassic extinction, but this extinction event induced the evolution of mammals on Earth which indirectly induce the evolution of humans. According to Smithsonian National Museum of Natural History (2007), the reasons of the dinosaur’s extinction are still being argued by paleontologists. Paleobiology researchers agree that a major cause was an asteroid about 10 kilometers in diameter that collide with Yucatán peninsula in Mexico. The aftermaths of the impact were catastrophic; possibly inducing global forest fires, long-period of cold weather due to smoke and dust blocked the sunlight, and followed by a period of hot temperature caused by the high levels of CO₂ released into the atmosphere (greenhouse effect). Evidence for these statement is the finding which paleontologist found cretaceous dinosaurs’ fossil under a layer of asteroid rocks layer. Some paleontologists claim that dinosaurs were deteriorating before the asteroid collision; hence its environmental aftereffects quickened their extinction. Besides, there is others fact to the plenty and diversity of dinosaur species fossil recorded in the sediments left underneath the asteroid impact layer in the Hell Creek Formation of western North America.

4) Cenozoic era

a. The Age of Mammals

Lastly, it is the Cenozoic era (65 million years ago to present). According to Hamilton (2010), the early stage of Cenozoic era was still dominated by descendants of dinosaurs, the birds even after the mass extinction of dinosaurs. But then, the land nowadays is dominated by mammals. Different habitat diversified mammals to herbivore, carnivore, and omnivore just in order to survive. During 65 million years ago, a type of mammals diversified and evolved into Plesiadapiformes, which believed it is the ancestor of primates (ape-liked mammals) (Dawkins, 2004). Throughout 50 million years of evolution, the first Hominidae (great apes) diversified as the descendants of gibbons. For another 12 million years of evolution, some great apes developed bipedal abilities (walking with two legs) and they are known as the ancestor of Homo mammals.

b. The Age of Humans

The Homo genus organisms was then evolved into Homo antessor, which as known as the ancestor of Neanderthals and modern humans (Bermúdez de Castro, et al., 1997). Until 200 thousand years ago, the first homo sapien with Y-chromosomes evolved and they were originated from Ethiopia, Africa. The population was then increasing and starting to migrate to all over the continents. Till now, it is the Age of Humans.

Reference

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· Chu, J., Massachusetts Institute of Technology, A possible cause of the end-Permian mass extinction: Lemon juice? 2013.

· Darwin, C., On the Origin of Species (By means of Natural Selection), London, 1859

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· J. M. Bermúdez de Castro, et al. A Hominid from the Lower Pleistocene of Atapuerca, Spain: Possible Ancestor to Neandertals and Modern Humans. Science 1997

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· Newitz, A., Phenomena: A science salon hosted by National Geographic Magazine, Lystrosaurus, 2013

· Richard Dawkins "Fossils that might help us reconstruct what Concestor 8 was like include the large group called plesiadapi-forms. They lived about the right time, and they have many of the qualities you would expect of the grand ancestor of all the primates" 2004

· Sci-news, Jack Hills Zircon: Scientist Discover Oldest-known Fragment of Earth, 2014

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< http://paleobiology.si.edu/geotime/main/htmlversion/cretaceous1.html>

· Smithsonian National Museum of Natural History, the Proterozoic: Eukaryotes and the first multicellular life forms. 2007

· Speer, B. R., University of California Museum of Paleontology, The Devonian Period, 1998

· University of California Museum of Paleontology, Geological Timescale: The Archaean eon and Hadean eon, 1997

· University of California Museum of Paleontology, See the world (and its fossils) with UCMP's field notes, the Cretaceous period, 1995 , < http://www.ucmp.berkeley.edu/mesozoic/cretaceous/cretaceous.php>

· Wang, D.Y.-C., Kumar, S. & Hedges, S.B. Divergence time estimates for the early history of animal phyla and the origin of plants, animals and fungi. Proceedings of the Royal Society of London: Biological Sciences 266,1999

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