5 pages describing the major discoveries regarding the universe, planet Earth, evolution of Homo Sapiens, genes and inheritance.

1. Essential Science - The Earth, Universe, Evolution and Genes.
1. Introduction
Scientific knowledge is created by: i) studying the structure and behaviour of the physical and
natural world through observation and experiment, and ii) producing a report or record.
Travel over long distances can stimulate interest in different environments. The Italians Marco Polo
(1254 – 1324) and Christopher Columbus (1451 – 1506) made long exploratory journeys over land
and sea. An expedition by Ferdinand Magellan (Portuguese) and Juan Elcano (Spanish) was first to
sail completely around the Earth between 1519 and 1522.
Nicolaus Copernicus (1473 – 1543) from Poland studied the motion of the planets and stars, and
issued a book stating that the Sun is at the centre of the Solar System rather than the Earth. His
diagram shows the Earth as a planet orbiting the Sun and located between the orbits of Venus and
Mars. This work, consisting of study followed by a printed record, started the Scientific Revolution.
Isaac Newton’s (1642 – 1726) book on the ‘Mathematical Principles of Natural Philosophy’ laid the
foundations of Mechanics in 1687. He produced laws of motion and gravitation, which explained
the motions of the moon and planets, and that the tides were caused by gravitation of the moon
and sun combined. Newton also studied optics and light.
Charles Darwin (1809 – 1892) studied medicine, geology and theology prior to travelling around the
world on the sailing ship named the Beagle in 1831-35. He took a small low-power microscope on
that voyage, but later had one with 1500 times magnification. Darwin collected specimens and
made notes at all the places he visited, including South America, the Galapagos islands, Australia
and South Africa. In 1859, he published his book entitled ‘Origin of Species’ which describes the
evolution of creatures by natural selection to suit their environment.
In 1968, the Apollo 8 spacecraft travelled to the Moon and looked back at the Earth. The 3
astronauts on board saw a large spherical piece of rock with 70% of its surface covered with water,
see photos below. The Earth is called a ‘Goldilocks’ planet, where the temperature is ‘just right’ –
‘not too hot’ to cause the water to evaporate, and ‘not too cold’ to cause all the water to exist as
ice. Water is considered to be essential for life to begin and evolve.

2. 2. Telescopes
In the year 1610, Galileo Galilei from Pisa, Italy, made a useful small telescope and reported
observations of 4 moons orbiting the planet Jupiter, which is at least 400 million miles away from
Earth. Galileo also confirmed that the Sun is at the centre of the Solar System - not the Earth. More
powerful telescopes have since found another 75 small moons orbiting Jupiter.
In 1923, Edwin Hubble, using the 100-inch reflector telescope at Mount Wilson, near Los Angeles,
saw that Andromeda was not a nebula (a cloud of dust and gas) but was a distant galaxy, 2.5 million
light-years from Earth. The distance travelled by light in one year is 5,900,000 million miles or 9.5
trillion kilometres. Up to 1923, it was thought that our galaxy, the Milky Way, was the only one in
existence. Astronomers estimate that our galaxy, with diameter of 100,000 light-years, contains
100 - 400 billion stars, many of which are orbited by planetary systems.
Our local star, the Sun, and its Solar System with 8 large planets plus dwarf planets and asteroids,
were formed around 4.6 billion years ago from the gravitational collapse of a dust and gas cloud.
This cloud resulted from an explosion of an earlier star (a supernova) which created the heavier
elements, including carbon and iron, by fusion of hydrogen and helium. In our experience on Earth,
carbon is the basic constituent of organic chemistry and is essential for life to evolve.
In 1990, the Hubble Space Telescope was installed to orbit 600km above the Earth so that
observations could be made without the distorting effects of the atmosphere. In 1995, it was
programmed to observe a very small patch of what was thought to be empty space for 10
consecutive days. This long exposure captured as much light as possible, and the resulting photo
(below) revealed around 3,000 galaxies, some of which are over 12 billion light-years from Earth.
Later Deep Field exposures probed as far as 13.4 billion light-years distance, from which
astronomers have estimated the age of the Universe at 13.8 billion years. The evidence suggests
that the Universe started with a Big Bang and is expanding from a single location. The present
estimate is that there are more than 2,000 billion galaxies in the Observable Universe (see
Wikipedia 2018), which has a diameter of more than 90 billion light-years.

3. 3. Evolution
From fossil evidence, life on Earth first appeared around 3,500 million years ago. This was
approximately 1,000 million years after the Earth was formed. The first living organisms were
cyanobacteria or blue-green algae, which grew by photosynthesis and were responsible for creating
the oxygen in the atmosphere. Almost 3,000 million years after first life, the first fish evolved with a
spinal column leading to all vertebrates. The amphibians evolved four legs from the four underside
fins of fish so that they could move on land. There have been 5 mass extinctions of life forms, and
the last one, an asteroid impact 66 million years ago, ended the dominance of the dinosaurs and
allowed the mammals to flourish.
Mammals have evolved to inhabit most environments – in the oceans: seals, sealions, and more
than 80 species of whales and dolphins; the Arctic: polar bears, seals; the Antarctic: Weddell seals;
and in the air: more than 1000 species of bats. Squirrel-type mammals evolved to move around
easily in trees, leading to the first primates or monkeys. The timeline from first life to humans is
detailed below, with figures denoting millions of years ago before the creatures first appeared.

4. 4. Microscopes
The first microscope was created in the early 1620s, probably in the Netherlands, but Galileo had built one in
1625. Robert Hooke, born in Freshwater, Isle of Wight, published a book in 1665 called Micrographia
containing drawings of his microscope’s images of insects and plants, see his flea and thin slice of cork
below. Hooke described the honeycomb-type structure of cork as built of ‘cells’. This was the first time the
word ‘cell’ was used to describe the structure of an organism.
Following the use of improved microscopes with high magnification, it is now known that all plants and
animals are constructed from cells. An amoeba is a small single-celled animal. More complex creatures begin
life as a single fertilised cell, and grow by cell division. A human embryo has 16 cells after 3 days, is 7 mm
long after 1 month and 10 cm long after 3 months. A human contains around 2,000 billion cells at birth,
rising to 37,000 billion in adulthood, with around 70% of them as red blood cells.
In the 1880s, German biologists using microscopes saw that the nucleus of each cell contain chromosomes
which divide when the call divides, so that every cell in an organism contains the same chromosomes.

5. 5. Genes and Inheritance
Chromosomes are thread-like structures in the nucleus of cells made of protein and a single
complex organic molecule of deoxyribonucleic acid (DNA). The long DNA molecule is made from
shorter sequences named genes which contain the specific instructions that make each type of
living creature or plant. In 1869, the DNA molecule was first isolated from white blood cells by
Friedrich Miescher in the University of Tubingen, Germany. The ‘double-helix’ structure of human
DNA was determined at Cambridge University in 1953 by James Watson and Francis Crick.
The genes instruct the cells to form particular features of an organism; such as limbs/hands/wings,
mouth/teeth/beak, eyes, the brain and its thought processes, etc. In the early stages of
development, the embryos of all vertebrates look very similar, see line A of the illustration below.
Later, just the mammals have similar appearance, see line B. However, nearer to birth (line C), the
mammals can be very different. This similarity during the early stages of development supports
Darwin’s Theory of Evolution, where the genes of each creature have been modified over time by
natural selection to suit its particular environment.
At human conception, the embryo receives 23 chromosomes from the mother's egg and
23 chromosomes from the father's sperm. These pair up, with one of the pairs determining the sex
of the embryo. The total of 46 chromosomes per cell contain approximately 21,000 genes. Each egg
and sperm contain a different combination of genes. This is because when egg and sperm cells
form, chromosomes join together and randomly exchange genes between each other before the
cell divides. This means that, with the exception of identical twins, each person inherits unique
characteristics – a random mixture of half of each parent’s genes.