Geological time scale Geological time scale is 2 chrono! ‘and development of the earth. The geo ‘two or more geological eras form an EON Jogical sequence of geologic and evolutionary events covering logical time scale is divided into €0N, 678s period, which is the largest division of geologic: fon + hundreds of millions of years: ra wo-or more geological periods comprise 2” 679 which is hundreds of milions of period : Theperiodisthe basic unt “of geological time in which single tYPe of rok ‘of millions of years:Cretaceous Jurassic hassle Silurian ‘Ordovician ‘Cambrian Vendian ‘Age of Invertebrates First amphibions fe First land plat fosss ‘stand plant “lobes dominant, Cambrian a‘of Human Evolution Histo, (1863) made first attempt to describe man’s origin in his book Man's Pace, in Er Be nd visualised apes asthe closest relatives, Later in EET, Charles Darwin advocated Nat out man’s ancestry in hs book The Descent of Man. However Scientific studies ie Mruman evolution started about one hundred year ago: "Most prehuman fossils were a from 1920 onwards, The first fossils of human ancestors were unearthed by Eugene disp, a Dutch anatomist ba iutions of Raymond Dat, W.C. Pe, Louis and Mary Leaky het son Richard and peed igenco, eave help in preparing tee of human evolution. [ai Xeet ~ TERTIARY PERIOD. MOceNe 23 loucocene 28 EOCENE 54 PALAEOCENE EPOCH [AROREAL INSECTIVOROUS ANCESTORS. Fig. 7.59 Phylogenetic treo of modem primates showing origin of ‘apes and man from some common ancestors ,ee eee ee A. Prior to Apeman i ae 1. Dryopithecus: It is a 8roup of apes whose fossils were eine Bore se i Mi {about 20-25 million years old) from Africa and Asia. Their fossils Sat ae hi ills in Bilaspur (India) have been named Sivapithecus and that from East Afri ryopith ‘africanus. * were of almost equal length, I ni eetheeus resembled great apes. is arms and legs were o ses posture anh st ems em modern apes. It supposed to be tesco “ancestor of ap and man. sreseconeul: Fossils of Proconsul were obtained from East Africa from Miocene rocks, forehead was man daca canines were very long and pointed like thone af apes. Chim and Gorilla are pres led gant Stole from Proconsl about 4 million year ago in Pli Therefore, itis also called a pre-ape, 3. Ramapithecus: Ramapithec Earliest man-like fossil obtained fro Pliocene about 10-15 million year, (a) Man-like feeding habits ©) Walking erect on the ground, 6) Canines smal, like that of man, (@) Short face and small brain (©) Thickly enamelied teeth {0 They could bend their knuckles rm Att to be the forerunner of Hominids, It was syarnica and Asia in the rocks of late Mioeage, and earl * 280. Ramapithecus was arboreal primate having: By molecular clock method, it w 8. The Apeman Sstablished that Ramapithecus w ‘98 ancestor to Orangutan, us (L. Australis = south + Pithecus xc discovered by Raynaud Dartin "eene rocks. It lived about 5 million ies with Apes) everaging about four feet, a Le *ting lower jaw)2 Hoga tbl rai Fossils of Homo hat ee ae ashe see was named handy man fossils in ake Turkana in Kenya. Ie 0% 82089 andy man smn re showed a gait. sn fone focenc. Homo habilis was about 4-6 feet in height. It sh b 8 Fn er et tan inp hal chara eee [aeEE than that of Aistalpithecus about 7 i lis was with a humanclike body Met damp head. He lived in caves and used to coleo! ces, mats tubers and other plan tr rereed, though raw meat was also eaten, They <1 oerpols of chipped stones tO dig Out MDE for ope skin and meat and crush animal bones. 8 Homo erectus (The Upright Man: The Forerunner ‘of Modern Man): Hom erectus evolves fron bls or Austalopitecis about 17 milion years 6° fiat fons were described Hees Fe wot Pthacanthropus (Gk. Pitheos = ape + anthrPe an) Its fossils have dee rava, Peking (China) and Heidelberg (Germany) fand Europe. i (a}-Homo erectus was around 5.5 feet tall {DyTls pelvis was more bow-shaped. (0 Theacetabulum was placed more inward than in Australopithecus, so that H. erectus had a straight-legged stance. (a) Foot was arched to support body weight. (6) Grasping ability of foot was completely lost. fands had perfected the 4G) H. erectus had a low sloping forehead, thick eyebrows and massive but less pronoucned ower jaw than in Australopithecus (h) The size of cranial cavity ranged. precision grip’ for holding twigs. =1100 ce toyco erectus was hunter and food gatherer. If used stone tools for HAA and butchering, dea Mitclopes, bears, wild oxen, etc. It also used tools made of wood ‘and bones. It lived in caves erin campe and had learnt the use of fire for cooking and used animal skin to clothe itself. Two forméof Homo erectus have been identified: “Homo erectus or Pithacanthropus erectus = Java apeman Tomo erectus pekine? sis or Sinanthropus pekinensis = Peking man C. The Early Man Homo eapiens: Homo sapiens (wise hominid) was the first mar: ike form whlch, appeared - in ie Mestocene epoch about {0,000 years ago. The fossils obtained from different parts of the iets vert escribed under different names. The important fossil groups belongin Homo sapiens are: F oot Sal {a) Homo sapiens heidelbergensis (Heidelberg man): Itis known only by a massive lower Twas found from Heidelberg, Germany. The jaw was large and heavy and lacked a cet Teath were like those of modern man. Heidelberg is regarded as an ancestor to Neanderthal man and contemporary to Homo erectus. (He sderthalensig (Neanderthal man)>Fossils of Ni le #( manyrPos ‘eanderthal man were ‘discovered in 1856 from a cave near Dusseldrof pete Valley, cee Previously, these were named Homo neanderthalensis. But now they are known as FH. sapien remderthaensis. They arose, some 1,00,000 years ago and flourished in Europe, ‘Asia and North Africa, but became extinct about 25,000 years ago. Its main features were: (i) The forehead was low and slanting itF The eyebrow ridgos-were-heavy. (ii) The lower jaw was strong with strong jaw muscles with no chin. =Ge) The capacity of cranial cavity was about 1300- 1600 Ge (1450 cc-POUENTS) MS cretccr | incomes man. But its lower and RRS AY posterior portions were larger than the upper and anterior parts, (Comcrir Watane MAN USED () They were about 1.5 to | NRE COOPERATE vanmwa 1.66 metres in height, ie., short-statured. Phortstat YSemi-erect stooping posture anderthals were intelligent and good hunters. They learnt to use and construct flint tools They used animal skin for UTHERN APE clothing and buried dead They are supposed t perform ceremonies and construct hut-like dwelling structures. They were contemporary to modern man. Most probably, the were wiped out by their more advanced cousins, the Cro-Magnon man, about thousand years ago or they were absorbed into the gene pool of modern man by interbreeding, (©) Homo sapiens rhodesiensis (Rhodesian Man): Fossils of Rhodesian man were found in Rhodesia in the large limestone cave. The skull had a cranial cavity about 1300 eyebrow ridges. It might be even Fig. 7.66 A-Different human-like forms during evolution ‘man; B-Tool making by Neanderthal man ce with receding forchead and hea more primitive than Java man, ‘arly Modern Man): Its fossils were disco. rth-west Italy and rock shelter caves in Francepanacea ence TT ‘5,Face was prognathous, £ Cranial capacity was 1650 fae ture: Cro-Magnon man was cave dweller and hunter. It had learnt 19 80) | nto excellent tools such as spearheads and fishing hooks. 1t hhad started making clothes bone animals’ hides. It probably believed in afterlife because it used to bury its se out ee artefacts. It had learnt drawing andl painting pictures of ‘contemporary animals 2500 j ‘ago. Cro-Magnon was one of the many human populations that developed the Palaeolithic culture in Asia and Africa too, It was Nomadic but had started settling downs Fefganent communities where food was abundant i. Homo sapiens sapiens (Modern Man): Its the living modern man. it probably evolved from Cro-Magnon man about 25 thousand years ago towards the ‘end of last glacial period. fide man is associated with Neolithic culture, He learnt to cultivate plants and domesticate Mamals of economic importance. It started settling down near lakes and ocean shores where it anid catch fish. Ithad started domestication of plants and animals about "10,000 years ago. The cor tes of farming are knovn from Indian subcontinent and Middle-east Neolithie revolution tattle the development of technological culture with the use of metals and preparing ellie tools, ornaments and utensils by smelting ores, Size of cranial cavity #8 1300-1600 cc {average 1450 co) HoMo SAPIENS FossiLis CSARGNON TAN) HOMO SAPIENS SAPIENS Howo SAPIENS ~ (MODERN MAN 'RHODESIENSIS S OND 4-5 m.Lon vas ‘A. ROBUSTUS <—_ 7 ee AUSTRALOPITHECUS oMILLONYRS| EARLY TAPRIGAN APEMAN) PLEISTOCENE aMaerecs {10-15 MLLION YRS| EARLY PLIOCENE PROCONSUL (EARLIEST MANAIKE PPINATE) ae (ANCESTOR OF APES). a DRYOPITHECUSANO SIVAPITHECUS 20-25 MILLION YRS | MIOCENE {FRONTAFFICA) (FROM INDIA) {ANCESTOR OF MAN AND APES) Fig. 7.57 Pedigree chart of human evolutionMolecular clock: ates of mdlecular evolution and smounts of gente vaaton can be measured I-can be estimated from the amine aid sequence ofa poten, or rucestie sequence of region of DNA ntwo of more species{The molecular Geek's a Fechnigue in mol TS_@ technique in molecular evolution to relate the time that the two species diverged to the number Of molec diferences measured between the species” DNA sequences or pratensis sometimes called a 9eNe chor evolutionary clock. The concept of meleclar cock i based on hypothesis hat DNA and prsin SEQUBNS Groive at a rate that is relatively constant over time and amang different organism. This constancy is used tO eats ie eit oF tre Wa various orgasms have been diverging from one anothe by measuring the Gages GFadiference between two sequences. The molecular dock hypothesis was orginally proposed by TeseBrehets Emile Zuckerkandl and Linus Pauling onthe basis of empirical observations, butt soon received theoretical Backing Wen biologist Motoo Kura developed the neutral theory of molecular evolution in 1968, \N6iitral theory of molecular evolution TH STG TE af molecular evolution (as, simply the neural theory of evalution) isan influent ony cee res ximura. Kimura suggested tat oorge fraction of new ntaens do net hsv anata Ceaonry Riess, so raturl election wold nether euro stance, rete SSRs ea aera hay spreod throughout a population ond become fixed in allot its members, ee¥heu would bs lst entirely ina stochastic proces called genetic ‘mute shed atte hich etal mats 2 he substitution rate) equivalent to the rate of Become fixed in a population (Known 88 i each member of the populgton (the mutation rts), cnt Oat i ea a ee ‘constant throughout the tree of life, He across species, the substitution rake would remain‘mura subsequently summarized his theory as follows: - This neutral theory claims thatthe overwhelming majrty of evokaionary caused by selection acting on advantageous mutants, but by random fixation of neutral mutants through the cumulative effect. ‘of sampling drift (due to finite, ‘input of new mutations.’ Thus, the neutral theory of molecular evolution predicts that the rate at which Particular position in the genome is equal to the mutation rate, as long as all the strictly neutral (thet is, they have no affect on organismal fitness). A controversy arose when Kimura's theory was published. Many evolutionary biologists the theory pointed out several important observations that had been recently reported, including + ‘synonymous base substitutions (ie. those that do not cause amino acid changes) occur at a) than non-synonymous substitutions. © Mutations occur at rate in non-coding sequences (such as introns) as compared to 7 Pseudogenes evolve at high rate as compared to functional genes.‘a period of just 1 million years. / by looking at Its odometer. To deduce 1 the car has been travelling. 1@ molecular clock, one must know the absolute ‘mammals and birds. An estimate of the tim or by correlating this particular instance of evolut (such as the formation of a mountain range that spl ‘age of some evolutionary diverg jing of this event can be gained jonary divergence with some lit the geographic range of a species of speciation). Once the evolutionary rate is calculated using 2 calibrations this ca d to other organisms to estimate the timing of evolutionary events, fossils suggest that the most recent common ancestor of humans and orangutans lived 13 BOO calibrate the human molecular clock, we can compare hyman and orangutan DNA sequeieg the amount of nucleotide substitution (0) that has occurred:\The rate of nucleotide substitutions Lee tions per lineage per million years (r) can be calculated as a time of most recent common