CRST 290 - History of Life
Introduction
From the time the Earth was formed to the present and up to the formation of the
different kinds of life forms including the human civilization the journey is best told in history. It
is important to know about this history to recognize the factors that have predisposed the
appearance of the present diversity of the life living on Earth. The timeline of life’s history is
briefly discussed focusing more on key events and emergent transitions in terms of geologic
time. By studying the beginnings of life, the emergence of service intelligent beings and the main
branches of evolution one can better comprehend the complexity of the living world.
Formation of Earth and Early Conditions
About 4. 6 billion years ago, our planet was born out of dust and a gaseous disc
surrounding the young star, the sun. This process is referred to as accretion by which mass was
gathered from the gaseous and solid material pulled by gravity. Conditions on early Earth were
harsh; they included: , and due to forces such as; active volcanoes, crust that has started forming
and meteorite impacts. In the first stage of evolution, the gases introduced to the atmosphere
included methane, ammonia, and water vapor; the atmosphere did not contain oxygen, hence,
can not support the modern organism.
Within these compressed parameters in this case, the Relative elements concerning the
planet Earth put in place the appropriate conditions for the emergence of life. These conditions
included the ability of the planet to cool down and form a crust as well as, water vapour which
on condensing, formed the oceans. The primitive seas full of dissolved mineral and organic
compounds participated in the formation of chemical processes which led to life.
+The first direction of the emergence of life was primordial with the formation of basic organic
molecules such as amino acids and nucleotides. This is why the Miller-Urey experiment in the
1953 is still remembered to this day because these basic molecules could be synthesized within
conditions presumed to be present on early Earth. This experiment reproduced the conditions of
a lightning strike inside a test tube with several flammable gases and obtained several organic
compounds; among which was some of the amino acids, the building blocks of proteins.
The Origin of Life
Origin of life on the Earth is considered one of the greatest unknowns that people are
searching for mainly in the sphere of sciences. Abiogenesis theories in the emergence of life
suggest that it is developed from the natural chemical system that may allow self-organization
bio-molecules. Including the continuous evolution of Hypotheses and references to the beginning
of life, this part is aimed at the transition from simple chemicals to the initial bodily structures.
Abiogenesis and the Formation of Organic Molecules
The concept of abiogenesis can be described as the formation of new forms of life out of
non living matters. Organisms that inhabited the early Earth that formed around 4. That formed 6
billion years ago, went through processes in a chemistry that was unique to that time and was
never repeated in the entire history of the universe. Simple molecules that existed in the original
atmosphere of the planet were methane (CH4), ammonia (NH3), water vapor (H2O), and,
hydrogen (H2) there was no oxygen, but there were lots of chemical elements.
+This experiment conducted in 1953 with the name Miller – Urey confirmed that the
necessary components of proteins or amino acids can be synthesized if conditions of the early
Earth are to be imitated. When electric spark was applied on a couples of lighting principles on a
mixture of these gases, several amino acids which are protein molecules were synthesized. This
extraordinary experiment provided strong philosophical matches that the organic molecules,
when needed for the synthesis of life, could be equally produced under pre-biotic atmosphere.
+ Studies conducted after this have noted that there could have been numerous site that
could have favored synthesis of organic molecules in early Earth like the hydrothermal vents,
geological activities and even the shallow seas. Regarding those structures one can distinguish
hydrothermal vents as the object of the interest because they provide different minerals and a
constant energy source; the environment is perfect for the abiotic synthesis of the organic
compounds.
The RNA World Hypothesis
The RNA world hypothesis is one of the conjectures made in the quest for the origin of
life which continues to be investigated. Based on this hypothetical model it is assumed that RNA
which has the capability of storing genetic information and is also capable of acting as a catalytic
agent and is capable of performing rather complex chemical reactions was a very useful tool
during this between life and non life phase. While replication of DNA, of which copy needs
proteins, RNA can be that and an enzyme, so it most likely was the first to self-replicate.
+Consequently, the facts that are the proof of the RNA world hypothesis and which will be
described further include the presence of so-called ribozymes, tests that are RNA molecules that
possess enzymational activity. Examples of biochemical reactions that may be catalyzed by
ribozymes are the RNA replication and the formation of the peptide bond. RNA is identified as
having the ability to replicate itself and given that self-replication systems can be obtained from
it, this formulates a reasonable understanding on how self-replication systems come about.
According to some theories, the first self-replicating RNA molecules arose in sea in early times
of the Earth, where elements like the nucleotides combined and from longer chains of RNA.
These RNA molecules would be capable of replication and on being mutated, would experience
action by natural selection and develop and increase in complexity and efficiency of replication.
The Transition to Prokaryotic Life
The first replication in RNA form probably led to the evolution of simple forms of life,
which eventually developed elaborate forms. These early life forms were prokaryotes, the first
and the simplest form of cells without a nucleus. Prokaryotes are bacteria and archaea which are
two domains of living organisms that are somewhat similar to each other but at the same time
very different from each other.
+Due to the scarcity of oxygen in the first few billion of years of Earth’s lifetime, it
became the domain of prokaryotes. Because oxygen was not present early prokaryotes had to
utilize anaerobic metabolic processes, one of which was fermentation. These several basic
metabolism activities enabled the prokaryotes to obtain various resources with habitats and
opened the path of evolution.
Photosynthesis and the Great Oxygenation Event
Undoubtedly, one of the largest occurrences in the book of life may be the birth of
photosynthesis. Photosynzing procaryotic organisms known as cyanobacteria started to release
oxygen to the atmosphere through this process about 2. 7 billion years back. The digestion which
was altering the compounds of carbon dioxide and water to the compounds of organic used to
free Oxygen. Compared to the currently developed scene, photosynthetic organisms have not
changed it publicly. Eventually, oxygen generated by cyanobacteria was released to the
atmosphere and it escalated to what is known as The Great Oxygenation Event (GOE)
approximately 2. 4 billion ages ago. This climactic change in the earth’s environment engaged
the stirring of destruction and construction of life forms on earth by the appearance of the aerobic
life forms.
The modification process was rather significant and touched upon the following major aspects of
the GOE:
1. Formation of the Ozone Layer: The rise in the oxygen content of the ambience was
beneficial to the creation of the orgone layer or the well-known ozone layer situated in
the stratosphere. This advantage was the protection of life forms from the fatal ultraviolet
(UV) radiation hence allowing life forms to exist on the exterior part of the Earth.
2. Evolution of Aerobic Respiration: The developments of aerobic respiration which is
widely used in almost all the living organisms occurred as a result of increased
availability of the substance, oxygen. In aerobic respiration the organisms seem to be in a
position to gain energy from the molecules that they need, hence creating room for the
other types of lives most of which require more energy than the other.
3. Ecological Changes: Surge in the utilization of higher amounts of oxygen and the
change that this indented on the chemical structure and composition of the atmosphere as
well as the ocean impacted on the richness and the composition of microbes. Some of the
anaerobic organisms were flushed out to other enclosed oxygen-free environments while
other organisms were shaped by the new environmental status.
The Role of Hydrothermal Vents and Alkaline Hydrothermal Systems
High temperatures and hydrothermal sources are believed to be good candidates to search
for the appearance of life. Ocean floors receive substantially little light because they are very
deep and comprise of a lot of minerals and a steady energy source that all promote prebiotic
chemistry.
+ Hydrothermal vents especially the black smokers again produce hot mineral-rich fluids in
the water of the surrounding area. These vents create high gradients of chemistry and order a
constant supply of power and reagents. When the substances from the vent fluids are combined
with seawater, it becomes possible to form organic products and develop the rudimental
metabolic connections.
Other concerning related environments such as the Lost City Hydrothermal Field offers
rather unique circumstances which belong to Alkaline hydrothermal systems. These systems are
also subjected to high pH or alkaline conditions and relatively lower temperatures compared to
those of black smokers. The structures of these systems become leaky and this means that there
are mini-niches that are created which allow there to be chemical reactivity so that molecules can
self replicate.
From Chemistry to Biology: The Formation of Proto-Cells
These following steps have marked the critical stages of transition from the simple
organic molecules to the living cells. The first step which paved way to the formation of cells
was the emergence of proto-cells, which are membrane bound bodies that have an interior
environment that differs from the exterior environment. Earlier types of cells offered a more
defined environment to the processes that happened in them and this was made possible in proto-
cells. By this kind of proto-cell lipid membranes created with the fatty acids or phospholipids
permitted these proto-cells to be formed. Lipid molecules can spontaneously self-organize into
bilayer structures if placed in an aqueous state this forms a barrier between the inner
environment and exterior environment. This barrier allowed for focus to be made on the
accumulation of organic molecules as well as forming appropriate metabolic networks.
+Consequently, proto-cells, presumably contained informational polymers, which could also
replicate and perhaps even catalyse reactions. Elements of cells such as RNA, lipids, and other
organic molecules of proto-cells may have laid down anchors for metabolisms as well as genetic
systems of the early days. Eventually these proto-cells became much more developed
prokaryotic cells the variety of which is present throughout the world at present.
The Rise of Eukaryotes
The second great divide in the history of life forms was the emergence of eukaryotic cells
or cells with a true nucleus and membrane-bound organelles. This was a very fundamental
advancement of life that enabled a progress to more advanced forms of life, organisms of greater
size and sophisticated structures.
Endosymbiotic Theory
The endosymbiotic theory in question can be also known as one of the most popular
theories specifying the evolution of the eukaryotic cells. This theory is based on the
consideration on the fact that eukaryotes are assumed to have developed from prokaryotic simple
organisms that had a symbiotic relationship. In this theory it is assumed that some of the
prokaryotic cells were engulfed and then swallowed by some greater host cells and then were not
assimilated. Instead, they carried out mutual interactions with the cell that were characterized by
mutual benefits to the host cell.
+
These engulfed prokaryotes then became sessile and became part of the host cell organelles like
today’s organelles. Out of all the vital organelles that are assumed and even have logical proof to
be developed in this fashion, mitochondria and chloroplast are widely recognized.
1. Mitochondria
Mitochondria is referred to as the powerhouse of the cell because the component is primarily
involved in the generation of energy via cellular respiration. According to research, the
endosymbiotic theory holds it that mitochondria arose from obligate aerobes, alpha-
proteobacteria. These bacteria were able to support oxidative phosphrylation hence efficient use
of energy. This relationship provided the host cell with the effect of the bacteria to produce ATP
when the bacteria was swallowed by the larger eukaryotic cell and meanwhile, the bacteria was
provided with protection as well as feed.
Based on these args several body of evidence has suggested the endosymbiotic theory in the
formation of mitochondria:
Genetic Evidence: They also have five base pair circular DNA like the bacteria
concerning the chromosomes. Accounting for the genes, there are proteins and RNA
which are required in the mitochondria and are governed by mtDNA at the same time
there exist other genes that have been transferred to the nucleus.
Double Membranes: Mitochondrial is enclosed by double membrane, this can be
understood through the process of how it is engulfed. Thus, the researchers have
hypothesized that the inner membrane has evolved from the plasma membrane of the
ancestor of the endosymbiotic bacteria, whereas the outer membrane from the host cell
membrane.
Independent Replication: Thus, it is can form a replication system almost but similar to
binary fission that bacteria are known to produce to form a new mitochondrion.
1. Chloroplasts
Chloroplasts are those organelles that take part in photosynthesis and is present in plants and few
algal groups. According to endosymbiotic theory the chloroplasts are supposed to be originally
oxygenic photosynthetic bacteria that were free living. Thus it must have been beneficial for the
cyanobacteria for the host which was an early eukaryotic cell in the manner that the latter was
capable of capturing light energy and building up chemical substances from the same.
+Evidence supporting the endosymbiotic origin of chloroplasts includes: Based on the main
premise of the endosymbiotic, the following can be described as facts for the hypothesis include
the following:
+
Genetic Evidence: Chloroplast has own circular DNA through which according to it, this DNA
is very much similar to cyanobacteria. This is factual because most of the genes, needed for the
photosynthesis process, are still to be procured from the chloroplast DNA.
Double Membranes: Similar to the case of mitochondria described above, chloroplasts are
surrounded by the outer and the inner membrane That delimits the fluid-filled structure.
Suggestively, what is shown here is that this area has developed from the cyanobacterial
membrane and that the outer membrane is the part of the host cytoplasmic membrane.
+Similarities to Cyanobacteria: Their structural relationship is to some extent related to that of
cyanobacteria and the organism containylakoid membrane which is used we in the LD reaction
in photosynthesis.
Evolution of Eukaryotic Cells
It was occasioned by the development of eukaryotic cells that moving the cellular complexities
and therefore the formation of various kinds of organisms. Therefore, it led to the compartments
having specific sets of functions which promoted effectiveness together with the regulation of
the metabolic processes. This compartmentalism of the cellular functions let the eukaryotic cells
perform relatively more complex and coordinated activities.
Development of Multicellularity
Another of the most significant outcomes of the process can be seen in the level of
multicellularity which is characteristic of eukaryotic evolution. Regarding the fact that all cells in
the more complex organism are of the same kind, it is essential to mention that there are a lot of
them, and every cell has its role in the multicellular organism, being grouped into tissues, organs,
and systems. In my opinion this specialization allow to attain a higher level of complexity and
also it can be modyfied while working.
+Thus, the opinion has been voiced that the multicellularity reappeared separately throughout the
evolution of various phyla, such as plants, animals, fungi, and some algae. The transition from
unicellular to multicellular life involved several key steps: Moving from single-celled beginnings
to multi-celled organism can be describe into several sub-stages:
1. Cell Adhesion: Cell adhesion is owed for all in progression to multicellular life more
especially organisms with tissues. This adhesion was accomplished through proteins that
could create the structural organizations that shut the cells.
2. Cell Communication: Each living organism can be divided into two categories at least,
those are individuals and ‘organism’, and the latter must possess the capacity for cells to
be able to get informed about the processes occurring within the organism and the ways
they should address them. It is done by helping signaling molecules and receptors in a
way that the cells acquire a method of recognizing a shift within its own vicinity and with
other cells.
3. Differentiation and Specialization: They then pile up to become body organs in multi cell
organisms in as much as cells start to differentiate to perform a specific function. This
means that there are gene and epigenetic features that possess the potential, enable cells
to undergo a process of differentiation to begin certain operations in the organism.
Implications for Evolution
The appearance of the eukaryotic cells and the evolution of the multicellular organisms
had quite significant effects on the development of life on Earth. These concepts facilitated the
process of development of such forms of life which have highly ramified forms and perform
various functions. The eukaryotic cells are more complex as compared to prokaryotic cells, thus
the higher-order facilities such as nervous systems, immune systems and systems of reproduction
evolved in eukaryotes.
+
Moreover, sexual reproduction known for eukaryotic cellular organisms allowed more incidents
of variation of genes within populations. Sexual reproduction involves the formation of gametes
and the subsequent formation of a new organism from such gametes founded by two individuals;
this manner of reproduction results to new gene attributes which increase the prospects of the
ability of a species to adapt as well as evolve.
The Cambrian Explosion
Approximately 541 million years ago there was a massive diversification event called the
Cambrian explosion and that is when the majority of the current established animal phyla were
first documented. It was for this age span of about 20-25 million years that high diversification
of various forms of life was recorded while the complexity of these organizations was observed
in the evolution of body parts that could perform specific duties in living organisms. The
Cambrian explosion is significant as it is the diversification of many of the animals that are
present today.
+
Thus, several factors could have led to the Cambrian explosion kind of radiation as many
people refer to it. While the concept of proposed perfection was not met, there is one theory
regarding the subject; the theory to explain the process assumes that an increase in dissolved
oxygen in the world’s oceans allowed for the development of bigger organisms. Another theory
is associated with the emergence of critical gene innovations, such as the Hox genes that limit
the body plan of Animals and contribute to the creation of different formations. Again, this
forced the hasty differentiation of polymorphic animal structures due to competition for prey
with the big and powerful carnivorous animals.
+
The Cambrian level of the fossil record is known to reveal a lot of peculiar and strange
species of organisms that do not have close evolutionary relation to the living organisms. For
instance trilobites which form part of the marine the arthropod’s species became extinct soon
after the end of the Cambrian period; they were diverse and abundant. There are other popular
Cambrian inhabitants; for instance, Anomalocaris was a large arthropod thought to have dined on
trilobites; Hallucigenia had like spines covering its body and numerous tentacles on one side.
They were of simple organization and organization, their habits therefore pointing to the fact that
Cambrian explosion was as experimental.
Colonization of Land
It is considered perhaps one of the biggest revolutions in the evolutionary history –
transition from water to land. Primitive plants and fungi developed into the first terrestrial life
forms, thus catering to the terrestrial operational needs. The pattern of early land plants for
example bryophytes evolved appendages like roots and leaves to facilitate absorption of water
and nutrient from the ground. These adaptions enabled plants to colonise the land which enabled
the formation of new habitats and the alteration of Earth’s surface.
+After plants, the terrestrial original animals such as arthropods and amphibians adapted
to fill new ecological roles. Habitat: Insects and some other arthropods were probably the first
animal group that colonized the land. The marine creatures then evolved into having
exoskeletons and jointed appendages that would help support the bodies and move in the new
environment or on the new terrestrial habitat. Limbless fishes that changed into amphibians were
the ones that were suited for both aquatic and terrestrial lives. These were the fish-like creatures
that manage to evolve lungs and limbs for mobility in the water and on the land.
+The conquest of land also initiated new evolutionary prospects and this caused the
expansion of the form of life. Essentially, the emergence of vascular tissues like xylem and
phloem enhances plant’s ability to transport water and nutrients contributing to the development
of larger and more complex plants. Like in the case of animals, the development of respiratory
and circulatory systems lets us reach improved metabolic rates and broad variety of body plans.
Mass Extinctions and Their Impact
In the several billion years of life on Earth, there have been several large scale extinctions
that have radically altered the development of life. Snychronous mass extintion events are
expressed by the sudden disappearance of a large portion of the species on the surface of the
earth. Volcanic eruptions, changes in climate or impacts of asteroid, such events shaped the
patterns of evolution and the make-up of life on the planet.
+Another massive invention that affected the world was during the mite Permian more
severally, 252 million years ago. Sometimes called the Permian Triassic extinction, this one
wiped out 96 percent of the ocean’s species and 70 percent of the species that lived on land. The
reasons for this extinction are still unknown today but the theories suggested are due to large-
scale volcanic eruptions, emission of methane, and shift in the ocean acidity. Permian-Triassic
extinction made a tremendous change in the biota of Earth and put an end into thematic
dominating and began with the emergence of the new ones.
+Other famous mass extinctions include the Cretaceous-Paleogene (K-Pg) extinction that
took place about 66 million years ago. This event is well known for the end of Mesozoic era and
general extinction of nonavian dinosaurs. The K-Pg extinction is hypothesized to have been due
to the volcanic eruptions along with the effects of a large asteroid/comet. Hence, there has been
change in the environment such as fires, darkness and climate, in this respect many species were
wiped out. Similarly, this event seems to have presented chances for surviving groups, as
mammals and birds for instance, to expand and adapt in new areas obtainable in the ecosystem.
+Although mass extinctions meant loss for life on Earth they served as milestones in the history
of life on the planet. They have even shifted entire balances of ecosystems so that new species,
and new evolutionary forms, can emerge. These are aspects of post-crisis regeneration and
diversification that prove the organismal innate proclivity toward survival and existence.
The Rise of Mammals and Primates
Following the evolution of the non-avian dinosaurs, apes attained groundbreaking distinct marks
roughly 65 million years ago through extinction and started to expand in probably every
ecological compartment. It was during this period that the major features of mammals emerged,
as this group of animals remained warm-blooded, grew hair and had rather complex brains.
Thus, mammals evolved for enhanced survival in different habitats ranging from water to land
especially the forests.
+Angiosperms which are the now dominant flora first appear in the Cretaceous period and
mammals seem to parallel them in terms of evolution. Foram gli sviluppati nuovi modi di
interazione ecologicatra i Mammiferoi e le Angiosperme: la polinizzazione e la disseminazione
delle piante recanti semi, portando a ulteriori specializzazioni delle due categorie di organismi.
+Among the specially, mammals have formed a chief group where primates turned out to be of
great importance. Some of the features of the primates include functions like grasping hands,
forward-facing eyes and large size of the brains. Arboreal adaptations characterized the first
primates, thus the ability to live in trees. Such a lifestyle hanging in trees benefitted the
stereoscopic vision essential for depth perception as well as muscular coordination.
+The specific line in the evolution of primates has passed through a path that finally led to the
development of hominids or the family of man. Bipedalism, that is walking on two legs, makes
hominids unique as the hands were now free to handle objects. The evolution of hominids is
documented by fossils that depict the early forms of hominids right from the Australopithecus
category to the genus Homo.
Human Evolution
The journey from the primordial hominid species towards the modern Homo sapiens is
thus filled with evolutionary changes in morphology behaviour and culture. The specimens that
have been riveting paleoanthropologists are Australopithecus and Homo habilis and Homo
erectus’s etc important for understanding the progressive evolution for such characteristics as the
bipedalism, tools, and large social units.
1Australopithecus
Australopithecus is one of the oldest genera of hominids that inhabited earth, 4 to 2
million years ago. Remains of Australopithecus species like the “Lucy” an Afarensian
Australopithecus show signs of bipedalism but there is a blend of traits both of the ape and the
human. These early hominids possessed reduced brain size from the current human beings but
displayed the following characteristics through the features of the fossils; bipedalism, arboreal as
well as terrestrial.
The year 1974 saw the discovery by Donald Johanson of the world-famous “Lucy”.
Conducting yet another examination of Lucy through the results of her skeletal structure it is
known that Australopithecus afarensis possessed the right pelvis and leg to support the upright
walking. Nevertheless, long arm and curved fingers indicate that they continued hanging more
often, probably on account of foraging and to evade carnivores. The bipedalism persistence of
Australopithecus shows a very transitory phase in Human evolution that between tree climbing
and ground living.
Homo habilis
The butchery techniques imply the presence of early Homo, in particular, Homo habilis,
which inhabited Earth 2. 4 to 1. 4 million years ago. Homo habilis also normally named as
handyman is distinguished by the use of primitive stone tools suggesting advancement in the
cognitive and motor skills. Tool use is believed to have marked our evolution, hence, listing the
evolution of tools as the first major step in human evolution.
Homo habilis was comparatively larger brained, who had an average encephalization
quotient of about 600-700 cubic cm. This growth in the size of the brain leads to the
enhancement of the aspects of cognition and the ability of performing intricate tasks. The
Oldowan tool industry with features of simple stone flakes and cores is associated with Homo
habilis. These tools were most likely to be used for carving, scraping and preparing food
materials thus being suggestive of a core adaptation strategy in man’s fight for survival as well as
for tool development to usurc resources.
1Homo erectus
The next important type is considered to be Homo erectus who existed, approximately,
1,9-million-110000 years ago. Homo erectus also possessed a relatively larger brain that is
approximately 900cm³, and a relatively more modern body build characterized by long lower
limbs and short upper limbs. It was also evident that this species engaged in the use of more
complicated tools and successive behavior patterns that entailed use of fire, thereby affecting
aspects of diet, social relations and existence.
+Homo erectus was able to manipulate fire; this eventual control inturned in sustenance to
become less complex to digest, thus boosting its nutritious value. In addition, cooking lowered
the incidences of food-borne diseases and led to the advancement of additional hierarchical
interpersonal relationships in subjects over food consumption. The Acheulean tool industry
relevant to Homo erectus is as developed as the earlier industry but more refined hand axes and
cleavers were made, therefore requiring advanced planning and tool-making skills.
+But this species of humans is also characterized by its widespread settlement across the
geography the world. Insuffices archeological data are available to suggest that Homo erectus
rose from African ground and populated Eurasia stretching from China and Indonesia. That
shows the flexibility and sustainability of Homo erectus in terms of the climate and other
circumstances.
Homo heidelbergensis and Homo neanderthalensis
Homo heidelbergensis whose time ranged between 600,000 and 200,000 years is also a
direct and close relative to Homo sapiens and Homo neanderthalensis. In comparison to Homo
erectus, Homo heidelbergensis’s brain volume was comparatively larger and it also made more
sophisticated tools than Homo erectus. This species is famous for chipping wooden spears and
using them to hunt big game, thus demonstrating the development of cooperation in hunting as
well as division of labor.
+Neanderthals, scientifically known as Homo neanderthalensis, inhabited Europe and some parts
of Asia half a million years ago to about forty thousand years ago. These were people with
stocky bodies and heavy bones; large and muscular and possessing rather large nostrils
conformed to living in the cold regions. They also displayed some such traits like tool making,
early uses of fire, constructions of shelters maybe and possible emergence of symbolism in
practices such as burial.
1Homo sapiens
+Neanthals, beside the Neanderthals, Homo Sapiens the species to which we belong to,
evolved about 200-300 thousand years ago in Africa. The physical and molecular anthropology
data point to the fact that Homo sapiens migrated slowly across the earth and had some degree of
gene flow with other hominids including Neanderthals and Denisovians. With the adaptation in
the communication skills, art and organisational complexity, Homo sapiens was able to form a
variety of cultures and societies.
+
The expansion of Homo sapiens out of the continent of Africa is well supported by the
evidences from the archeological findings as well as the DNA prints. The Homo sapiens arrived
in the Near East about 100000 years ago and gradually occupied the regions of Europe, Asia,
Australia, and America. This migration involved the changes to numerous habitats and creation
of various cultures.
+
They are evident in the form of tools used and developments in their thinking and culture
as displayed in the fossil record. The Upper Paleolithic or the later phase that started 50,000
years ago marked the dawn of more creativity and the development of superior tools along with
paintings, sculptures, and organic instruments. All of these cultural manifestations express the
highly developed social hierarchy and symbolic turn that defines our species.
Interbreeding and Genetic Legacy
1The recently conducted research on genetic sequencing has shown that Homo sapiens had
matting with other species of the hominid group including Neanderthals and Denisovans. Their
copulation has genetically affected today’s human race. For instance, Europeans and persons of
non-African descent have about 1-2% Neanderthal admixture; some Asian and Oceanian
populations possess Denisovan admixture. GEs have been associated with many aspects of the
current human biology; immunological measures and high altitude accustomation included.
1Conclusion
The record of life on the planet shows that through evolution living organisms have
developed an inherent ability to survive. Climbing from the easy molecules to the modern
biomes, life has passed through quite several transitions. Knowledge this history brings not only
information about the origin of human beings but also the relationship between all the living
creatures on the Earth. Thus, by delving deeper into the learning of the early years of life, we can
acknowledge the factors that formed the differentiation the existence of life on our planet and
discover more possibilities for further evolution.
+Earth life is characterized by relatively short and dramatic bursts of variations and new
creations and longer epochs of mass extinctions. All these have formed what today we get to see
in the masquerade of life’s abundance. The interest of life process journey starts from the simple
prokaryotic organisms and then gradually became relatively complicated Eukaryotic organisms,
The initial animals of Cambrian explosions, the process of civilization, how they migrated from
water to land and the effect of mass extinction, the birth of mammals and then the evolution of
mankind.
+
In this case, the history of life becomes important when we need to stand a modern
advent that is climate change, habitat destruction, and loss of species. It makes us reflect on the
strong survival instinct of the species, the depth of the relation between living organisms and the
people that have the responsibility to decide on the fate of our planet. Studying previous events
enables us to make better decisions in the current world and help create a healthy future for all
living organisms.
