People with colour blindness cannot tell the difference between certain colours, or they may not see colours at all. Most colour blindness is inherited as a genetic condition.
There are far more males who are colour blind than there are females. Between five and eight percent of males, but less than one percent of females, are colour blind.
The most common form of colour blindness is red-green colour blindness. The Ishihara Color Test is the test most often used to diagnose red-green colour deficiencies.
The test consists of a number of coloured plates, called Ishihara plates, each of which contain a circle of dots appearing randomized in colour and size. Within the pattern are dots which form a number visible to those with normal colour vision and invisible, or difficult to see, for those with a red-green color vision defect.
For example, a person with normal colour vision would see the number 74 below, while a person with a red-green color vision defect would see only spots.
Now, an Italian court has cut the sentence given to a convicted murderer by a year because he has genes linked to violent behaviour — the first time that behavioural genetics has affected a sentence passed by a European court. Read more here or here.
WOW!
So basically, this guy has five genes (including the MAOA gene) that have been linked to violent behaviour, and as a result, the court thinks it is more OK for him to commit murder than someone else. It’s like the murderer is being excused for committing murder.
Medical advances mean that many people who once would have died young now live to a ripe old age. This has led to a belief that natural selection no longer affects humans and, therefore, that we have stopped evolving.
That belief has now been shown to be flat out wrong.
Women of the future are evolving to be slightly shorter and plumper, have healthier hearts and longer reproductive windows.
In a recent study it was found that shorter, heavier women tended to have more children, on average, than taller, lighter ones. Women with lower blood pressure and lower cholesterol levels likewise reared more children, and – not surprisingly – so did women who had their first child at a younger age or who entered menopause later. Strikingly, these traits were passed on to their daughters, who in turn also had more children. Read more here or here.
Australian researcher Elizabeth Blackburn (and Carol Greider and Jack Szostak of the United States) have won the Nobel Prize for Medicine for identifying a key switch in how cells age.
The trio were honoured for discovering how chromosomes are protected by telomeres and the role of an enzyme called telomerase in maintaining or stripping away this vital shield. It’s groundbreaking research into a possible “fountain of youth”. Read more here or here.
To explain all that a bit:
Living things are made up of cells and cells are controlled by a molecule called DNA. In cells DNA forms structures called chromosomes. Humans have 23 pairs (total of 46) of chromosomes – you get 23 from your Mum and 23 from your Dad. Chromosomes look like this:
They have a centromere in the middle and telomeres on the end. Telomeres play an important role in ageing. As you get older your chromosomes get shorter and shorter because every time your cells replicate they lose a little bit of telomere at the ends.
When they get too short, the cell can no longer divide and it dies. And I suppose when all the telomeres in all of your cells get to short you’re in trouble!
Elizabeth discovered (among other things) if telomerase levels are high, the telomere length is maintained, cellular ageing is slowed, and you don’t get old. Read even more here or here.
As of today, humankind may have a new mother, and she looks nothing like we expected her to.
Researchers have unveiled the oldest known skeleton of a human ancestor–and it is full of surprises. Although the creature, named Ardipithecus ramidus, had a brain and body the size of a chimpanzee, it did not knuckle-walk or swing through the trees like an ape. Instead, “Ardi” walked upright, with a big, stiff foot and short, wide pelvis. Read more here, here, here, here or here.
This is a picture of a real apple picked from a real apple tree:
Horticulturists say the colourings on the apple are probably caused by a random genetic mutation. If the genetic mutation took place within the apple, it is likely to be a one-off occurrence. However, if the mutation occurred in the tree, there could be similar coloured apples next year.
The mutation is known as a chimera where one of the first two apple cells have developed differently, giving rise to one half of the apple being different from the other. Read more here.
Squirrel monkeys can now see your true colours, thanks to gene therapy. Researchers have given the colourblind primates full colour vision as adults by injecting their eyes with a human gene. The result could eventually lead to gene-therapy treatments for colourblindness and other visual disorders in humans.
In the world of squirrel monkeys, seeing colours is for girls. Whereas some females enjoy full colour vision, males see only blues and yellows (see picture). They lack a gene that allows color-sensitive cells in the eye, called cones, to distinguish red and green from gray–the same distinction that confounds most colorblind humans. Read more here, here, here or here.
An ovum (plural ova) is a female reproductive cell or gamete. If a female reproductive cell gets fertilized by a male reproductive cell a new animal grows and develops.
For example, if a chicken ovum is fertilzed by a male chicken, a baby chick will develop.
If a chicken ovum is NOT ferilized by a male chicken the chicken ovum, or egg, may very well end up being eaten by a human.
In very rare cases female chickens produce ‘ovum in ovo’, or an egg within an egg. This occurs when the normal development of the egg malfunctions in some way. See:
Scientists are only months away from creating artificial life!
The first artificial lifeform is likely to be a simple man-made bacterium that proves that the technology can work. But it will be followed by more complex bacteria that turn coal into cleaner natural gas, or algae that can soak up carbon dioxide and convert it into fuels. They could also be used to create new vaccines and antibiotics. Read more here.
Don’t you hate those people who are perky and efficient after only a few hours of sleep. They can’t help it. New research suggests that a genetic mutation may explain why some people sleep less.
Scientists have found that an abnormal copy of a gene called DEC2, which is known to affect circadian rhythms and oxygen regulation in mammals, can result in people needing far less sleep than average. When the scientists bred mice to have the same mutation, the mice slept less and were more active than their regular rodent peers.
Scientists say the average adult needs eight to 8.5 hours of sleep each night to function optimally, but the short-sleepers reported feeling great on a lifetime average of only 6.25 hours per night. And unlike most of us, who catch up on sleep whenever we take vacation, the mutation carriers stuck to their short sleep schedule even when they had no responsibilities.
The Human Genome sequence was finished in 2001. That is 3,000,000,000 bits of information were decoded and put in order – a BIG job.
Interestingly, the first human genome cost billions of dollars and required an army of scientists, but now a trio of researchers has matched that feat for the price of a mid-range luxury car. Soon you’ll be able to get your entire genome sequence at the corner store for a buck. Reminds me of a movie I once saw. Read more here.
Well, at conception (when the sperm meets the egg) a human is a single cell, and from this single cell, hundreds of different cell types arise. Basically, this means that that one cell (called a stem cell) has the potential to become all the different types of cells that will eventually form a living human.
As the organism ages, the stem cells split and “differentiate” into cells that are more specific (for example muscle cells, brain cells, skin cells or blood cells).
Getting back to teeth …
If you’ve lost a tooth to decay or injury, you may not have to rely on that dental bridge or implant forever. Scientists have found a way to bioengineer new adult teeth. So far, the method only works in mice, but it may one day take hold in humans.
Researchers created a “tooth germ” from mouse stem cells, implanted the 500-micrometer (0.02-inch) germ inside a mouse’s tooth socket, and waited.
A month later, a new tooth erupted from the gum. The stem cell tooth was as hard and sensitive as a natural tooth, though the new tooth glowed green in ultraviolet light (pictured).
The team had attached green fluorescent protein to the tooth germ to better track the genes that were activated as the tooth grew. Read more here or here.
A species is the basic category of biological classification. It is a group of organisms that differ from all other groups of organisms, and that are capable of breeding and producing fertile offspring.
That last bit, producing fertile offspring, is an important part. For example, a male donkey (Equus africanus asinus) and a female horse (Equus ferus caballus) can mate but the offspring, a mule, is infertile. This means that a mule and a mule can’t produce more mules and so a mule is not a species.
Similarly a tigon is a cross between a male tiger (Panthera tigris) and a female lioness (Panthera leo). Infertile and thus not a species.
Lastly, a liger is a hybrid cross between a male lion (Panthera leo) and a tigress (Panthera tigris). Interestingly, Ligers are also the largest big cat in the world! See:
All living things are made up of cells. When organisms need to produce new cells to grow, or replace damaged or dying cells, copies of pre-existing cells are made by a process called mitosis.
Cells are controlled by a molecule called DNA. It contains a complex set of instructions which makes us who we are. When cells reproduce via mitosis they must make an exact copy of their DNA first.
If you’d like to see what it looks like when DNA copies itself, check out this animation:
