Key developments in 2005 in the area of physical anthropology included the dating of the oldest-known fossil members of Homo sapiens, the first reported chimpanzee fossils, surprising findings about gene expression associated with the X chromosome, and intriguing genetic insights pertaining to the evolution of the human brain.
The Omo I and Omo II specimens, H. sapiens fossils from the Kibish Formation in southern Ethiopia, were originally thought to be approximately 130,000 years old, but they were redated with argon-isotope measurements on feldspar crystals from volcanic deposits located slightly below the fossil levels. The new preferred estimate of the age of the specimens was between 190,000 and 200,000 years, which made them the earliest well-dated members of H. sapiens. Prior to this redating, the oldest reported human fossils were three crania (H. sapiens idaltu from the Bouri Formation in the Afar depression of Ethiopia) that were argon-isotope dated to between 154,000 and 160,000 years ago. The new date for the Omo specimens was in striking agreement with many recently determined mitochondrial DNA-based dates that placed the origin of H. sapiens at approximately 200,000 years ago.
Although thousands of hominin (hominid) fossils had been reported over the last 150 years, not a single chimpanzee (Pan) fossil had been documented. A 2005 report described three fossil chimpanzee teeth (two upper central incisors and an upper first molar) that were found in the Kapthurin Formation, Kenya, and demonstrated that chimpanzees were present in the East African Rift Valley contemporaneously with an extinct species of Homo. A fourth fossil tooth (possibly an aberrant upper third molar) was also found but was not described. Argon-isotope dating bracketed the age of the specimens to between approximately 284,000 and 545,000 years old; however, stratigraphic positioning implied a date closer to the maximum age of 545,000 years. The upper incisors were nearly identical to those of modern Pan except that they had shorter roots. Both the extremely low crown of the upper first molar and the pronounced thinness of its enamel distinguished the tooth from those of known hominins. The three teeth probably came from one individual that died at the age of seven or eight years. The fossil chimpanzee remains were about 600 km (about 375 mi) east of the limit of the current range of Pan, which made it possible that chimpanzees and hominins were sympatric (lived in the same area) since the time of their evolutionary divergence.
An international consortium of genome centres succeeded in determining almost all of the DNA sequence of the human X chromosome and documented the extent to which the human Y chromosome had decayed in its nonrecombining regions. The X chromosome contained 1,098 genes, but exons (expressed gene regions) accounted for only 1.7% of the X-chromosome sequence. Only 54 of these genes had functional homologues (similar counterparts) on the human Y chromosome. Perhaps the most unexpected finding regarding the human X chromosome was the extensive variability in X-linked gene expression in human females. In most female mammals one of the two X chromosomes becomes randomly inactivated early in development. Since males have only one X chromosome, this inactivation results in a comparable level of gene expression for X-linked genes in females and males. Some of the genes, however, escape inactivation and are expressed from both the inactive and the active X chromosomes of a female. A comprehensive gene-expression profile for a sample of inactivated X chromosomes found that about 15% of X-linked genes regularly escape inactivation to some degree. Surprisingly, an additional 10% of X-linked genes yielded variable patterns of inactivation and are thus expressed differently in different females. These differences in gene expression might help explain both sex-specific phenotypes and variations in phenotypes between females.
Two genes that regulate brain size were shown to have undergone positive selection in human populations during the last 40,000 years. Six genetic loci were known that could lead to primary microcephaly (an abnormally small brain) as the result of recessive mutations. One of these gene loci, microcephalin (MCPHI), was thought to control the proliferation or differentiation (or both) of immature nerve cells in the formation of nervous tissue. A haplotype (haploid genotype) with a derived allele was found to have a much higher frequency than other haplotypes at this locus. Numerous statistical tests demonstrated that this haplotype was under strong positive selection. Frequencies of the favoured haplotype were found to be highest in Eurasia and the Americas and lowest in Africa. Additional calculations estimated the age of the haplotype to be approximately 37,000 years, a date that coincided with the arrival of modern humans in Europe and with the increased presence of art and symbolism that was characteristic of the Upper Paleolithic culture. The second gene locus, abnormal spindle-like microcephaly associated (ASPM), might regulate the proliferation or differentiation (or both) of neural stem cells during brain development by mediating spindle assembly during cell division. One haplotype at this locus had an unusually high frequency and differed from other haplotypes at a number of polymorphic sites, two of which were in a region that had previously exhibited particularly strong positive selection in humans. The favoured haplotype had noticeably higher frequencies in Europeans and Middle Easterners than in other populations. Additional statistical tests confirmed the indications of positive natural selection for the derived haplotype and estimated its age at approximately 5,800 years. The age and geographic distribution of this haplotype across Eurasia roughly coincided with important cultural innovations such as the domestication of plants and animals (approximately 10,000 years ago) and the development of cities and written language (5,000–6,000 years ago). As intriguing as these biocultural correlates were, their significance had not yet been established.
In 2005 the conflict in Iraq continued to take its toll on cultural treasures in the cradle of civilization, particularly at the 5,000-year-old Sumerian sites of Umma and Isin. In April the upper part of the 52-m (171-ft) 9th-century spiral minaret of Malwiya at Samarra was damaged by a mortar attack. The ongoing pillage of archaeological sites, primarily in the southern provinces, continued at an alarming rate, but few of the antiquities had yet surfaced on the international art market.
A devastating earthquake in Iran on Dec. 26, 2003, which precipitated the collapse of the massive mud-brick citadel Arg-e-Bam, proved fruitful for archaeology by revealing layers of civilization long buried by later construction. Among the finds reported in 2005 were a series of settlements and relics that dated from the time of the citadel’s founding, in the Achaemenid period (6th–4th century bc), through the Islamic period and that elucidated the chronology of the inhabitation of the fortified city of Bam, the largest mud-brick construction in the world. Also in Iran, construction of the Sivand Dam threatened numerous archaeological sites, including Paleolithic rock shelters, rock-cut tombs from the Elamite period (c. 2700–c. 650 bc), and the well-known tomb of Cyrus the Great (590/580–c. 529 bc) at Pasargadae.
Continued excavations at the 23,000-year-old campsite of Ohalo II on the shore of the Sea of Galilee in Israel yielded evidence for the processing of wild wheat and wild barley 10,000 years before the domestication of either grain. Dolores Piperno of the Smithsonian Institution and colleagues reported that starches and seed remains from the grains were found embedded in a grinding stone at the site. What was believed to be the earliest-known rendering of the Hebrew alphabet—22 letters carved in the correct sequence some 3,000 years ago on a 17-kg (38-lb) stone—was found by Ron Tappy of the Pittsburgh Theological Seminary and colleagues at Tel Zayit, a site in the Beth Guvrin Valley not far from Jerusalem.
Elsewhere in the Near East, excavations continued at Tell Sabi Abyad in Syria, where what was believed to be the oldest pottery in the world was found. Dated to between 6800 and 6300 bc, some two centuries earlier than the previous record holders, the dozens of rough, reddish-brown earthen water pots, jars, and jugs were simple in shape and had been made without the use of a potter’s wheel, according to Peter Akkermans of the National Museum of Antiquities in Leiden, Neth., and colleagues.
In Niger, deep in the Sahara, archaeologist Elena Garcea of the University of Cassino, Italy, and her team unearthed seven Stone Age settlements, including a large cemetery, on an ancient lakeshore. Thought to have been occupied between 10,000 and 5,000 years ago—before the once-verdant landscape dried up following the last Ice Age—the sites contained abundant stone tools, personal adornments, pottery fragments, and the remains of mollusks and catfish.
The remains of a 3,250-year-old glass factory, including a glass ingot and hundreds of ceramic crucibles, were found at the ancient Egyptian capital Qantir-Piramesses in the eastern Nile delta. The find attested to ancient Egypt’s role as a major producer of glass ingots. Prior to this discovery, made by Thilo Rehren of University College London and Edgar Pusch of the Pelizaeus-Museum in Hildesheim, Ger., scholars believed that the primary source for glass well into the middle of the 1st millennium bc was Mesopotamia, where glassmaking was thought to have begun around 1600 bc. Zahi Hawass of Egypt’s Supreme Council of Antiquities and an international team of radiologists, pathologists, and anatomists completed a comprehensive CT scan of the mummy of King Tutankhamen (who ruled 1333–23 bc). Hawass stated that contrary to what had been previously thought, there was no evidence that King Tut had been murdered. Although Tut was only 19 when he died, the team found no evidence of either a blow to the back of the head, which many believed to have been the cause of his demise, or any disease. The researchers noted that he may have broken his left femur shortly before his death but that the injury would not have been enough to kill him.
In the mountains of Swabia in southwestern Germany, archaeologist Nicholas J. Conard and co-workers from Tübingen (Ger.) University unearthed what was believed to be the world’s oldest musical instruments, a 35,000-year-old flute fashioned out of a wooly mammoth tusk and two smaller flutes made of swan bones. The Ice Age instruments were found in a cave in the Ach Valley. In Hohle Fels Cave, also in the Ach Valley, the same team discovered what was considered to be one of the earliest-known representations of male genitalia, dated to 28,000 years ago. The researchers stated that the polished life-sized stone phallus had markings that indicated that it had been used to knap (split) flints. Also in Germany, archaeologists found a female counterpart to the Adonis of Zschernitz, an 8,200-year-old clay statuette, discovered in 2003, that was the earliest-known Neolithic male figurine.
Excavations in Ireland and England conducted ahead of construction projects led to more than a dozen discoveries. John Kavanagh and co-workers from the National Museum of Ireland who carried out excavations at a site where construction was planned north of Dublin unearthed a 9th-century Viking burial of a 25–35-year-old woman who had been interred wearing a tweed garment with a bone comb and a gilded-copper brooch of Scandinavian origin. In eastern England archaeologists working ahead of the construction of a housing development at Colchester, Essex, the first Roman capital of ancient Britain, found the remains of a chariot racing track from the 2nd century ad and a well-preserved tiled bathhouse chamber. Also in England, a scrap of gold foil found in a Norfolk garden was identified as a Roman lamella, or magical charm, of which only a few dozen had ever been found. The charm bore an inscription that beseeches the protection of the Near Eastern god Abraxas for a soldier from the Rhineland.
What were identified as the oldest-known noodles were found in an earthen bowl at the 4,000-year-old site of Lajia on the Huang Ho (Yellow River) in China. The noodles, discovered by Maolin Ye of the Chinese Academy of Social Sciences and analyzed by Houyuan Lu of the Chinese Academy of Sciences and colleagues, were 50 cm (20 in) long and had been made with two strains of millet.
Excavators from the Kimhae (S.Kor.) National Museum found in South Kyongsang province what they purported to be the oldest fishing boat in the world. The remains of the boat were 3 m (10 ft) long and 0.6 m (2 ft) wide and dated to around 6000 bc. The boat, which was made of pine, was believed to have been originally at least 4 m long.