Lead poisoning has been found in the remains of two Neanderthal children who lived 250,000 years ago. The discoveries are the earliest known cases of the condition that can cause irreversible brain damage. The man-made pollutant was discovered in the remarkably preserved teeth of the young individuals in present day France. Scientists say they may have inhaled it from the smoke of fires lit to keep themselves warm and roast rhinos, horses and red deer they hunted. Food or water they consumed could also have been contaminated.