Senses >>> blood vessels The total length of all the blood vessels in the human body is about 97,000 km. This is over twice the circumference of the Earth's equator. >>> eating In a lifetime we spend the same amount of time eating as we do blinking. We spend about five years eating, and about five years with our eyes shut because we are blinking. >>> brain cells As we get older the brain loses almost one gram per year because its nerve cells die and cannot be replaced. >>> skin flakes We discard about 10 billion skin flakes every day. Over a year this mounts up to nearly two kilograms. >>> brain size A mouse has a larger ratio of brain size to body mass than a human, it used to be believed that this ratio was a sign of intelligence - if this were true mice would be about twice as clever as humans. >>> nerve Of all the nerve receptors in the human body, pain nerve endings are the most common. >>> sensitive The most sensitive parts of the body are the fingers and lips whilst the least sensitive part is the middle of the back. >>> eye A rod in the human eye can detect a single photon of light. This is the amount of light that might reach the eye from a candle, a mile away. >>> tongue The life span of a taste bud is ten days but the cells are constantly being renewed, roughly one every ten hours. Achievements >>> population It is estimated that in mid 2001, there were 9,000 people aged 100 and over in the UK. >>> left-handers ItA left handed person finds it easier to open a jar than a right handed person. This is because a left handed person can supply a stronger anticlockwise turning force than a right handed person. However a right handed person will find it easier to tighten the jar up afterwards. >>> freefall In 1960 Joe W. Kittinger, Jr. jumped from a weather balloon 32 kilometres above the Earth's surface. This is above the ozone layer and well above the height that jet planes fly at. During his freefall he reached the speed of sound. >>> cn tower The tallest structure in the World - the CN tower in Toronto - is over half a kilometre high. >>> speed of light Einstein's theory of relativity actually shows that everything is not relative. The speed of light is always the same no matter how fast you are going - away from or towards the beam. Future >>> stroked Research has shown that plants grow better when they are stroked, so a new machine has been invented which strokes seedlings as they are geminating, producing stronger, healthier plants. >>> temperature In the last 50 years the temperature of the Antarctic has risen by 2.5 degrees Celsius and may be to blame for icebergs breaking away from the continent. In 1995 a 1000 square kilometre iceberg broke off and started to float north. Evolution >>> fern The complexity of the organism has no bearing on the number of chromosomes it has: humans have 23 pairs of chromosomes while a species of fern holds the record for the most, with 630 pairs. >>> silkworm The silkworm moth (Bombyx mori) is the only completely domesticated insect. They are no longer found in the wild and have been cultivated for so long that they cannot fly. >>> mulberry leaves Silkworm larvae require a tonne of mulberry leaves to produce a 5kg of silk. Back