"This achievement effectively closes the book on an important volume of the Human Genome Project," said Simon Gregory, who headed the sequencing project at the Sanger Institute in England.

The project was started in 1990 to identify the genes and DNA sequences that provide a blueprint for human beings.

Chromosome 1 is the biggest and contains, per chromosome, the greatest number of genes.

"Therefore it is the region of the genome to which the greatest number of diseases have been localized," added Gregory, from Duke University in the United States.

The sequence of chromosome 1, which is published online by the journal Nature, took a team of 150 British and American scientists 10 years to complete.

Researchers around the world will be able to mine the data to improve diagnostics and treatments for cancers, autism, mental disorders and other illnesses.

Final chapter

Chromosomes, which are found in the nucleus of a cell, are thread-like structures that contain genes that determine the characteristics of an individual.

The human genome has an estimated 20,000 to 25,000 genes. The sequencing of chromosome 1 has led to the identification of more than 1,000 new genes.

"We are moving into the next phase which will be working out what the genes do and how they interact," Gregory told Reuters.

The genetic map of chromosome 1 has already been used to identify a gene for a common form of cleft lip and palate. It will also improve understanding of what processes lead to genetic diversity in populations, according to Gregory.

Each chromosome is made up of a molecule of DNA in the shape of a double helix which is composed of four chemical bases represented by the letters A (adenine), T (thymine), G (guanine) and C (cytosine). The arrangement, or sequence, of the letters determines the cell's genetic code.

The scientists also identified 4,500 new SNPs--single nucleotide polymorphisms--which are the variations in human DNA that make people unique.

SNPs contain clues about why some people are susceptible to diseases like cancer or malaria, the best way to diagnose and treat them and how they will respond to drugs.

Scientists had thought humans and chimps shared a common ancestor, but split about 6.5 million to 7.4 million years ago.

Previous research on the split of the species focused on average genetic differences.

Lander and his colleagues took advantage of the full genetic codes of humans and chimpanzees to estimate the age of sequences, rather than relying on an average.

'Evolutionary smoking gun'

If early humans and chimps separated, interbred and then parted ways again, it would explain the young nature of the human X chromosome.

"[T]he speciation itself occurred in an unusual manner that left a striking impact across chromosome X," Lander said in a release.

"The young age of chromosome X is an evolutionary 'smoking gun.'"

The two species split no more than 6.3 million years ago and probably no more than 5.4 million years ago, the team said in Thursday's issue of the journal Nature. That's one to two million years more recent than previous estimates.

The team plans to use the complete genome sequence of the gorilla and other primates to refine their timeline of when humans and chimps became separate species.

Scientists found that the two basic sounds - ''pyows'' and ''hacks'' - which are used to warn against different predators can be combined to mean something quite different. The monkeys call out ''pyows'' to warn against a loitering leopard and ''hacks'' are used to warn about hovering eagles overhead. However, combining pyow and hack means something like ''let's go'', according to scientists from the University of St Andrew's.

''To our knowledge, this is the first good evidence of syntax-like natural communication system in a non-human species,'' said Klaus Zuberbühler, one of the researchers.

The putty-nosed monkeys in the study live in the Gashaka Gumti National Park in Nigeria and were frequently heard using different sounds in response to different threats. Kate Arnold, the other member of the team, said that she became aware that the monkeys used several ''pyows'' followed by a few ''hacks'' as a way of telling a group to move away to safer terrain.

''These calls were not produced randomly and a number of distinct patterns emerged. One of these patterns was what we have termed a ''pyow-hack sequence'. This sequence was either produced alone or inserted at certain positions in the call series,'' Dr Arnold said.

''Observationally and experimentally we have demonstrated that this call sequence serves to elicit group movement in both predatory contexts and during normal day-to-day activities such as finding food sources,'' she said.

The scientists demonstrated in a study published in Nature that they would imitate the communication syntax of the monkeys by playing recorded calls to the wild troop living in the forest.

''The pyow-hack sequence means something like 'let's go' whereas the pyows by themselves have multiple functions and the hacks are generally used as alarm calls,'' Dr Arnold said.

''Previously, animal communication systems were considered to lack examples in which call combinations carried meanings that were different to the sum of the meanings of the constituent elements,'' she said.

''This is the first good example of calls being combined in meaningful ways. The implications of this research are that primates, at least, may be able to ignore the usual relationship between an individual call and any meaning that it might convey under certain circumstances,'' Dr Arnold added.

Sounding off: how animals communicate

* DOLPHINS

While it is not known whether dolphins have a formal language, they do have a signature whistle to identify themselves. Though they lack vocal chords, their sphincter muscles produce a complicated series of moans, trills and clicks. When a dolphin sees an object in the distance, particularly in murky water, it emits clicking sounds and listens to the echo to identify distance and object size.

* BIRDS

Bird calls are used to express alarm, and to keep members of a flock in contact, whereas songs ­ which mainly come from male birds ­ are used to claim territory or advertise for a mate. Basic song is the same for all members of a species, and it is believed that young birds learn the details of songs from their fathers. As variations build up over generations, they form a dialect. In a 2005 study in Science, it was shown that the number of "dees" in a chick-a-dee call corresponds to the degree of danger that a predator poses.

* WHALES

Whales communicate and navigate through sound. The best-known whale communication is the song performed by male humpback whales during the mating season. The song is believed to be part of sexual selection, but whether the songs are "flirting" from male to female, competitive behaviour between males or a means of marking territory is still the subject of research.

* FROGS

Frogs have a complex system of calls, the most notable when they have returned to the body of water where they were born. The male frog then uses calls to attract a mate, either by themselves, or collectively as a chorus. In some species of frog, including Polypedates leucomystax, the female frog will reply to the call. If mounted by another male, the frog emits a release call. Tropical species use a callto signal the start of rain. The only call the frog makes with its mouth open is the high-pitched distress call.

"Some of the most deeply ingrained economic behaviors turn out to be very, very ancient and hardwired parts of our decision-making processes," said Yale economics professor and the study's lead author, Keith Chen. "If I showed a string of capuchin monkey data to an economist, he couldn't, with any statistical test, tell the difference between a capuchin monkey and your average American stock market investor."
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In every 20-year period of American history, Chen said, a person who invested in stocks rather than bonds would end up making far more money. This is true, he said, even if the person had invested the Monday before Black Tuesday in 1929. Stocks, while riskier, always do better in the long run than the slowly-but-steadily appreciating bonds.

However, the average investor has puzzled economists by choosing to invest far more in bonds than is profitable, Chen said.

This odd phenomenon of risk aversion is one example of loss aversion-guarding against losing what you have over going for what you can get.

In a similar experiment, the Yale researchers trained monkeys to use money by providing them with coins and teaching them to purchase food from different vendors. One seller showed the monkey two apple slices, but when the monkey paid, half of the time the seller would only give the monkey one slice. Another showed one apple slice but half the time provided a second, bonus slice.

Instead of consistently buying from the vendor who presented the stronger visual cue of two apples or realizing that the expected return from either vendor was equal and buying from both vendors, the monkeys regularly chose the one who gave the bonus.

"Loss aversion behavioral economics intuition says, 'Well, wait a minute: One of these guys half the time delivers you a loss, whereas the other guy half the time delivers you a gain,'" Chen said. "And if you like gains and you dislike losses, in fact the monkeys should prefer trading with the guy who walks around only displaying one piece of apple. And in fact that's exactly what they do."

Chen further affirmed that we are no better than monkeys by saying our similarities are quantitative as well as qualitative, with capuchins weighing loss almost exactly as much as we do.

"Not only in types of behavior but even in levels of behavior," Chen said, "these monkeys look just like us."

When property manager Ryan Froerer got a call from a realtor last year to check on a townhouse, he knew something was up.

Ryan Froerer, Century 21: "Said it was the sickest thing he's ever seen. Just unimaginable that someone could live in that."

He couldn't even open the front door. It was blocked from inside.

Ryan Froerer, Century 21: "There was beer cans I would say probably this high up on the door."

The realtor had forewarned him about the smell.

Ryan Froerer, Century 21: "He poked his head in, the smell was so awful he couldn't go in. "

At the back door, Froerer was astounded by what he saw in the kitchen.

Ryan Froerer, Century 21: "As we approached the door, there were beer boxes, all the way up to the ceiling."

Inside, he took just a few snapshots to document the scene. Beer cans by the tens of thousands. Mountains of cans burying the furniture. The water and heat were shut off, apparently on purpose by the tenant, who evidently drank Coors Light beer exclusively for the eight years he lived there.

Ryan Froerer, Century 21: "It's just unbelievable that a human being could live like that. "

To all outward appearances, the person who lived in the townhouse was the perfect tenant. He always paid on time and he never complained. He kept a low profile in the neighborhood.

Kirk Martin, Letter Carrier: : "Yeah I never delivered any mail there at all. I thought the apartment was vacant."

The cans were recycled for 800 dollars, an estimated 70,000 cans: 24 beers a day for 8 years.

Froerer e-mailed his photos to a couple of friends, who sent them to friends. Now he's getting calls from faraway places

Ryan Froerer, Century 21: "It's amazing how the internet can have the effect and get around. I'm sure it's been around the world. "

The townhouse was cleaned up last year and it's just fine today.

The man who lived there seems to be back on his feet. We spoke to him today and he says he's completely stopped drinking. He was welcomed back to his old job a few months ago, and his co-workers speak highly of him.