PinkMonkey Online Study Guide-Biology
12.1 Palaeontological Evidences -Our Ancestors
Fossil records of human evolution is quite incomplete
and we have much to learn yet. In 1863, T.A. Huxley explained human evolution
in his book Manís Place in Nature. In 1871, Charles Darwin published
his ideas of human evolution in the book The Descent of Man. Later
on many attempts have been made to find the missing link between
man and ape in the form of an original creature or its fossil. Eugene
Dubo unearthed the first fossil record of an ancestor of man in the form
of a small part of skull and jaw bone. Between 1920 to 1930 many human-like
fossils were found in China called "Peking Man" or Sinanthropus.
But these fossil evidences do not form a neat chain of links leading from
ancient ape to the modern human.
It appears from the fossil evidence,
that human and apes have both descended from a common ancestor, called
Dryopithecus, that lived over 20 million years ago. At about the
same time the first human-like fossils were found in India and Africa
in the form of such primate genera as Ramapithecus and Sivapithecus.
The arrangement of teeth was like our own, indicating that Ramapithecus
was one of our ancestors. The next known genus Australopithecus africanus
(1.5 to 3 millions years ago) appeared in Africa. It had a rounded skull
with a brain capacity of 450 to 700 cm3
(compared to 1000 to 2000 cm3
for humans), apparently walked upright, and was about 5 feet tall.
Some controversy still exists about these human ancestors and
the gaps in evolutionary sequence, because the relevant fossils are rare,
the remains did not survive until now, or have not yet been found.
There is less controversy over the more recent stages
of human evolution. The fossils are more abundant and there are fewer
gaps. They show that Homo erectus, the first known member of our
genus, followed Australpithecus. Some 2 to 3 million years ago
Homo erectus emerged as an erect, bipedal creature, with a receding
forehead and human-like skeleton. Remains of H. erectus have been
found in Africa, South East Asia and China.
The first fossil that belongs to our own species, Homo
sapiens, appeared as recently as 100,000 to 40,000 years ago, and
resembles us so closely that we call it human (Fig. 12.2). Homo
sapiens survived as a result of erect bipedal posture, increased
manual dexterity, feet suited for walking and running, and
better developed creative brains.
Archeological records of human
evolution indicate that early humans started out as small bands of hunters
who killed animals for food and supplemented this with foraged and gathered
items. The hunt-gatherer cultures allowed humans to exploit agriculture,
about 10,000 years ago. Humans began to farm seriously around 8,000 BC
and there was full fledged agriculture in many places just after 4000
BC. The agriculture allowed establishment of
and the development of technology permitted the survival and growth of
Table of Contents
12.1 Palaeontological Evidences - Our Ancestors
12.2 Ancestral Forms of Homo Sapiens