news and views a key component in the semiconductor- 2. Kato, Y., Myers, R. C., Gossard, A. C. & Awschalom, D. D. Nature primate species. As expected for one of the device toolbox. I 427, 50–53 (2004). earliest known euprimates, the dentition is 3. Merzbacher, E. Quantum Mechanics (Wiley, Michael E. Flatté is in the Optical Science and New York, 1970). relatively primitive. The upper and lower Technology Center and the Department of Physics 4. Landau, L. D. & Lifshitz, E. M. The Classical Theory of Fields jaws both contain four premolars on each and Astronomy, University of Iowa, Iowa City, (Pergamon, New York, 1975). side (the maximum known for any primate) Iowa 52242, USA. 5. Yafet,Y. Solid State Phys. 14, 1–98 (1963). and the front premolars are not as reduced as 6. D’yakonov, M. I. & Perel’,V. I. Sov. Phys. JETP 33, e-mail: [email protected] 1053–1059 (1971). in other Teilhardina species. Certain dental 1. Purcell, E. M. Electricity and Magnetism (McGraw-Hill, 7. Kalevich, V. K. & Korenov, V. L. JETP Lett. 52, 230–235 (1990). features, and its small body size, suggest that New York, 1984). 8. Dresselhaus, G. Phys. Rev. 100, 580–586 (1955). the animal was an insectivore. The bigger picture is outlined in Fig. 1, which reflects the widely accepted view that Palaeontology there is a basic dichotomy in the primate evolutionary tree — one lineage leading to modern lemurs and lorises (strepsirrhines), Chinese lantern for early primates the other to tarsiers, monkeys, apes and Robert D. Martin humans (haplorhines)3–5.All or most Eocene primates are allocated to two major groups, A fossil skull from China, dating to 55 million years ago, provides much- lemuroids and tarsioids. These are comm- needed substantial evidence of early primates in Asia. Interpretation of only linked to modern strepsirrhines and the creature’s eye size and activity pattern will spark debate. haplorhines, respectively (although both could possibly have arisen from an indepen- he first fossil evidence for ‘primates of of this issue1). The authors allocate the fos- dent northern radiation of primates6,7). Teil- modern aspect’ — the euprimates — sil to a new species of the genus Teilhardina, hardina is included among tarsioids as a Tappears abruptly in the northern con- which was originally established for frag- potential relative of haplorhines. tinents at the beginning of the Eocene, mentary material from Belgium2. As well as the new species (T.asiatica),and about 55 million years ago. Eocene primates The new skull has several euprimate char- the originally described T. belgica2, the genus are well documented from sites in North acteristics, notably a bony ring around each Teilhardina currently includes five other America and Europe, but specimens from eye-socket (orbit), forward rotation of the species from North America. On this basis, Asia have been scarce and fragmentary. orbits and a relatively large braincase.But the then, Teilhardina seemingly had a remark- That situation changes with the report by skull is very small, with an overall length of ably wide distribution. Using characters Ni et al. of a well-preserved partial primate about 25 mm, and the animal’s body mass is derived from the new skull,Ni et al.1 repeated skull, with lower jaws, from China (page 65 estimated as 28 g — less than in any modern an earlier analysis of primate relationships5. The results confirm the basic primate Haplorhines Figure 1 Primate dichotomy, and are striking for Teilhardina evolution in outline. itself. Teilhardina asiatica and T. belgica Strepsirrhines This tree incorporates together constitute the earliest offshoot from the results of the the haplorhine side of the tree, branching off analysis by Ni et al.1 before the split between other tarsioids and 0 (see Fig. 3 on page 67; haplorhines (Fig. 1). By contrast, T. ameri- Lemurs Lorises Tarsiers Higher lemuroids are formally cana (the only American species considered) primates known as Adapiformes, lies within the cluster containing all other and tarsioids as tarsioids, reflecting a pronounced separation 10 Omomyiformes). Along from T. asiatica and T. belgica. Inclusion of with Teilhardina T. americana and other closely related North belgica, the new species American species in the genus Teilhardina is T. asiatica branches therefore questionable, as is the apparent 20 away first on the extensive distribution of the genus. haplorhine side of the Another unusual feature of T. asiatica is tree (T1). By contrast, the small size of the orbits relative to skull T. americana (T2) is length. Analysis of the scaling of orbit size nested within the other using a published data set8 indicates that this 30 Eocene tarsioids, species falls on the best-fit line for modern Lemuroids Tarsioids calling into doubt its diurnal primates, which generally have rela- Million years ago place in the genus tively smaller orbits than nocturnal species. Teilhardina. (Primate From this, Ni et al.1 infer that T. asiatica was 40 icons drawn by diurnal. They go on to interpret the evolu- Lucrezia Beerli-Bieler.) tion of nocturnal versus diurnal habits among primates, and conclude that the last common ancestor of euprimates was a 50 diurnal,visually oriented predator. This is an important issue, one on which T2 I have to disagree with the authors on both T1 statistical and biological grounds. Prediction from regression lines beyond the range of 60 ? ? the original data is suspect, and T. asiatica is smaller than any modern primate. In fact, ? Ni and colleagues excluded all large-bodied 22 © 2004 Nature Publishing Group NATURE | VOL 427 | 1 JANUARY 2004 | www.nature.com/nature news and views primates from the original data set, so alter- reduced in diurnal mammals — indicates ing the slope of the best-fit line for diurnal the degree of development of tactile whiskers primates and strengthening the inference for non-visual orientation. that T. asiatica was diurnal. Furthermore, no I believe, then, that we remain in the dark account was taken of the potential problem of with respect to the activity pattern of T.asiat- ‘phylogenetic inertia’9: closely related species ica. Regardless of that, however, Ni and may not be statistically independent, so esti- colleagues’ discovery is notable not only for mates of probability may be open to doubt. its implications for primate systematics but 100 YEARS AGO Biologically,one cannot assume that early also from a biogeographical perspective. Under the title of “The Case for Vaccination,” primates (particularly if unusually small in Until recently, it was widely held that direct Mr. C. E. A. Winslow gives an admirable size) showed the same functional patterns as migration of mammals between Asia and survey of the statistical data in favour of modern primates — which themselves are Europe around 55 million years ago was the efficacy of vaccination (Science, July 24, very variable. Given that ancestral primates ruled out by a transcontinental marine bar- p. 101). It points out that a single vaccination descended from ancestral mammals with rier. The landmass of Eurasia was largely or greatly reduces the probability of an attack of smaller eyes, early primates presumably completely split down the middle by a com- small-pox, postpones it to a later period of showed only moderate enlargement of their bination of the Western Siberian Obik Sea to life, and renders it less dangerous if it does eyes, regardless of their habits. In early pri- the north and the Turgai Straits to the south. ensue. To ensure absolute protection mates, the brain was less than half the size So it was suggested that the only possibility revaccination is required. During the small- of the brains of their modern relatives3.So for interchange of mammals between Asia pox epidemic of 1871, of 734 nurses and processing of visual inputs was probably and Europe was indirect migration across attendants in the Metropolitan Asylums Board more rudimentary, perhaps explaining why the Bering Straits, through North America Hospitals 79 were survivors from small-pox some Eocene lemuroids had far smaller and across the Greenland landbridge, or vice attack, and escaped infection; 645 were orbits than modern diurnal lemurs. versa.However,the presence of closely related revaccinated on entrance, and all escaped; 10 Another source of information comes Teilhardina species in China and Belgium were not revaccinated, and all took small- from a study by Kay and Kirk8. To increase (but not in America) in the early Eocene adds pox. Mr. Winslow concludes, “if statistics ever visual sensitivity in dim light, nocturnal to evidence that migration between Asia and proved anything, those quoted prove the species show marked retinal summation of Europe did not necessarily involve such a protective influence of vaccination.” inputs from the photoreceptors, resulting in roundabout route10. I From Nature 31 December 1903. a narrower optic nerve. This is reflected by a Robert D. Martin is in Academic Affairs, The Field narrower opening (foramen) for the optic Museum, 1400 South Lake Shore Drive, Chicago, 50 YEARS AGO nerve in the back of the orbit. For living pri- Illinois 60605-2496, USA. Scientific centenaries in 1954. The modern mates, Kay and Kirk found a good match e-mail: [email protected] use of a surname is so well established that it between activity pattern and relative size of 1. Ni, X., Wang, Y., Hu, Y. & Li, C. Nature 427, 65–68 (2004). is worth recalling that, as late as the fifteenth the foramen. However, all Eocene primates 2. Simpson, G. G. Bull. Am. Mus. Nat. Hist. 77, 185–212 (1940). century, hereditary surnames were by no 3. Martin, R. D. Primate Origins and Evolution: A Phylogenetic means general, it being the custom to add to have a small foramen, regardless of whether Reconstruction (Princeton Univ.