Archaeologists had a field day when they found remains of the oldest Europeans in Spain, but in Israel they are in trouble.

Discoveries that change understanding of human evolution are a rare occurrence but for a team of Spanish archaeologists they are becoming an everyday event.

The team, headed by Eudald Carbonell from the archaeology department at Tarragona University, Jose Maria Bermudez of the National Museum of Natural Science, and Jose Luis Arsuaga of the palaeontology department of Madrid's Complutense University, is credited with finding the oldest human remains in Europe at a site in Atapuerca, northern Spain, in July 1994. Their findings continue to revolutionise accepted belief about the first Europeans.

Human beings first evolved in the Rift valley of East Africa and started moving northwards through the Palestine Corridor to the Middle East about 1.5 million years ago. They spread out across Asia and moved to Europe 500,000 years ago. Scientists have always been puzzled by the comparative lateness of the colonisation of Europe.

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The findings at Atapuerca, a range of limestone hills near Burgos, have changed all that. Excavations have been under way there for the past 15 years. In July 1994 this patience was rewarded when a set of human teeth were dug up in the Dolina Trench, the largest of three sites. This was soon followed by 50 more fragments of fossilised bone belonging to four individuals, and some primitive stone tools.

Geomagnetic dating techniques subsequently established that the remains were at least 780,000 years old, almost 300,000 years older than the Mauer jawbone or Boxgrove Man, both contenders for the title of Europe's oldest inhabitant.

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Dr Carbonell said: "Everything we knew about evolution in Europe a year and a half ago now has to be reassessed." He believes that the Atapuercans could be the missing link between the early African species and Heidelberg Man who lived in Europe about 400,000 years ago.

In 1995, another individual was unearthed at the Dolina trench, and the other two sites also yielded up interesting finds. The team is even becoming a little blase. "We have got used to digging up skulls and jawbones," says Dr Carbonell. "Each year we find 200 to 300 fragments of human remains, something unheard of in the history of archaeological digs."

In the Sima de los Huesos or Bone Cave, reached by crawling along a narrow tunnel, bone fragments of 35 individuals have been discovered. Although, at a mere 300,000 years old they are much younger, they represent the best example of a group of the human population at the time. The extremely dry conditions in the cave mean that the find also includes delicate parts of the human skeleton that usually do not survive the effects of weather and time.

With such a large control group, the team has been able to come up with surprising insights into how people lived at that time. Human existence was short if not sweet - typical life expectancy was only 35. Dr Carbonell believes that hygienic conditions must have been quite good as there is no evidence of diseases.

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"In any case, they died so young they did not have time to develop cancer or any of the illnesses we suffer from," he says. Females began reproducing in their early teens, and at 1.5 metres high, tended to be much shorter than their mates who could be anything up to 2 metres tall. The basic social structure was a compact family group and the scientists believe that parents must have looked after their offspring well as none of the remains were of children.

Atapuerca is undoubtedly one of the richest archaeological sites in Europe. Excavation in the field is only carried out one month of every year with the rest reserved for processing all the new data those four weeks of frantic digging have yielded. Dr Carbonell believes that Atapuerca's potential is vast and that the site will keep them busy for many years to come. "At Dolina, we have found five individuals in six square metres," he says. "just imagine when we have excavated 200 square metres."