Question

Q.9. In what ways amphibians and reptiles have adapted to live on land? In your opinion which of these animal groups is better adapted to live on land? Q.10. Describe the evolutionary history of human starting with the ancestral primates about 55 million years ago?

Answer 1

Solution

Q9-

• The Reptiles have many adaptations for living on dry land that amphibians do not have
• For example, the tough waterproof scales that form the outer layer of their skin (epidermis) are made of keratin, the same protein that your hair and nails are made of. They cannot breath through their skin like amphibians can; instead, they breath entirely through their lungs.
• Actualy Most reptiles lay amniotic eggs covered with leathery or calcium-containing shells so This allows the eggs to be laid on land. Amphibian eggs have a jelly-like outer layer and need to be laid in water.
• Here Another feature that distinguishes reptiles from amphibians is that they develop directly into the terrestrial body form with limbs and a thick, scaly skin. They do not go through metamorphosis from a larval stage into an adult form like amphibians do.
• The amniotic eggs of reptiles are very different than the eggs of amphibians. The amniotic egg was one of the evolutionary developments that allowed vertebrates to move permanently onto land and away from the water, which amphibians need to prevent their eggs from drying out.
• So reptiles are more suited on land for there survival than the amphibians.

Q10

Human hiatory of evolution

• Timeline: Human Evolution

  55 million years ago (MYA)

  First primitive primates evolve

  8 – 6 MYA

  First gorillas evolve. Later, chimp and human lineages diverge

  5.8 MYA

  Orrorin tugenensis, oldest human ancestor thought to have walked on two legs

  5.5 MYA

  Ardipithecus, early “proto-human” shares traits with chimps and gorillas, and is forest-dwelling

  4 MYA

  Australopithecines appear. They have brains no larger than a chimpanzee’s – with a volume around 400 – 500 cm3 -, but walk upright on two legs. First human ancestors to live on the savannah

  3.2 MYA

  Lucy, famous specimen of Australopithecus afarensis, lives near what is now Hadar, Ethiopia

  2.7 MYA

  Paranthropus, lives in woods and grasslands, has massive jaws for chewing on roots and vegetation. Becomes extinct 1.2 MYA

  2.5 MYA

  Homo habilis appears. Its face protrudes less than earlier hominids, but still retains many ape features. Has a brain volume of around 600 cm3

  Hominids start to use stone tools regularly, created by splitting pebbles – this starts Oldowan tradition of toolmaking, which last a million years

  Some hominids develop meat-rich diets as scavengers, the extra energy may have favoured the evolution of larger brains

  2 MYA

  Evidence of Homo ergaster, with a brain volume of up to 850 cm3, in Africa

  1.8 – 1.5 MYA

  Homo erectus is found in Asia. First true hunter-gatherer ancestor, and also first to have migrated out of Africa in large numbers. It attains a brain size of around 1000 cm3

  1.6 MYA

  Possible first sporadic use of fire suggested by discoloured sediments in Koobi Fora, Kenya. More convincing evidence of charred wood and stone tools is found in Israel and dated to 780,000 years ago

  More complex Acheulean stone tools start to be produced and are the dominant technology until 100,000 years ago

  600,000 YA

  Homo Heidelbergensis lives in Africa and Europe. Similar brain capacity to modern humans

  500,000 YA

  Earliest evidence of purpose-built shelters – wooden huts – are known from sites near Chichibu, Japan

  400,000 YA

  Early humans begin to hunt with spears

  325,000 YA

  Oldest surviving early human footprints are left by three people who scrambled down the slopes of a volcano in Italy

  280,000 YA

  First complex stone blades and grinding stones

  230,000 YA

  Neanderthals appear and are found across Europe, from Britain in the west to Iran in the east, until they become extinct with the advent of modern humans 28,000 years ago

  195,000 YA

  Our own species Homo sapiens appears on the scene – and shortly after begins to migrate across Asia and Europe. Oldest modern human remains are two skulls found in Ethiopia that date to this period. Average human brain volume is 1350 cm3

  170,000 YA

  Mitochondrial Eve, the direct ancestor to all living people today, may have been living in Africa

  150,000 YA

  Humans possibly capable of speech. 100,000-year-old shell jewellery suggests that that people develop complex speech and symbolism

  140,000 YA

  First evidence of long-distance trade

  110,000 YA

  Earliest beads – made from ostrich eggshells – and jewellery

  50,000 YA

  “Great leap forward”: human culture starts to change much more rapidly than before; people begin burying their dead ritually; create clothes from animal hides; and develop complex hunting techniques, such as pit-traps.

  Colonisation of Australia by modern humans

  33,000 YA

  Oldest cave art. Later, Stone Age artisans create the spectacular murals at Lascaux and Chauvet in France

  Homo erectus dies out in Asia – replaced by modern man

  18,000 YA

  Homo Floresiensis, “Hobbit” people, found on the Indonesian island of Flores. They stand just over 1 metre tall, and have brains similar in size to chimpanzees, yet have advanced stone tools

  12,000 YA

  Modern people reach the Americas

  10,000 YA

  Agriculture develops and spread. First villages. Possible domestication of dogs

  5,500 YA

  Stone Age ends and Bronze Age begins. Humans begin to smelt and work copper and tin, and use them in place of stone implements

  5,000 YA

  Earliest known writing

  4,000 to 3,500 BC

  The Sumerians of Mesopotamia develop the world’s first civilisation