How and when did hominins move from the numerical cognition that we share with the rest of the animal world to number symbols? Objects with sequential markings have been used to store and retrieve numerical information since the beginning of the European Upper Palaeolithic (42 ka). An increase in the number of markings and complexity of coding is observed towards the end of this period. The application of new analytical techniques to a 44-42 ka old notched baboon fibula from Border Cave, South Africa, shows that notches were added to this bone at different times, suggesting that devices to store numerical information were in use before the Upper Palaeolithic. Analysis of a set of incisions on a 72-60 ka old hyena femur from the Les Pradelles Mousterian site, France, indicates, by comparison with markings produced by modern subjects under similar constraints, that the incisions on the Les Pradelles bone may have been produced to record, in a single session, homologous units of numerical information. This finding supports the view that numerical notations were in use among archaic hominins. Based on these findings, a testable five-stage scenario is proposed to establish how prehistoric cultures have moved from number sense to the use of number symbols.This article is part of a discussion meeting issue 'The origins of numerical abilities'.

a b s t r a c tIn 1993, a fossil hominin skeleton was discovered in the karst caves of Lamalunga, near Altamura, in southern Italy. Despite the fact that this specimen represents one of the most extraordinary hominin specimens ever found in Europe, for the last two decades our knowledge of it has been based purely on the documented on-site observations. Recently, the retrieval from the cave of a fragment of bone (part of the right scapula) allowed the first dating of the individual, the quantitative analysis of a diagnostic morphological feature, and a preliminary paleogenetic characterization of this hominin skeleton from Altamura. Overall, the results concur in indicating that it belongs to the hypodigm of Homo neanderthalensis, with some phenetic peculiarities that appear consistent with a chronology ranging from 172 ± 15 ka to 130.1 ± 1.9 ka. Thus, the skeleton from Altamura represents the most ancient Neanderthal from which endogenous DNA has ever been extracted.

The evolution of the cholinergic (nicotinic) receptor in chick muscles is monitored during embryonic development with a tritiated a-neurotoxin from Naja nigricollis and compared with the appearance of acetylcholinesterase. The specific activity of these two proteins reaches a maximum around the 12th day of incubation. By contrast, choline acetyltransferase reaches an early maximum of specific activity around the 7th day of development, and later continuously increases until hatching. Injection of a-toxin in the yolk sac at early stages of development causes an atrophy of skeletal and extrinsic ocular-muscles and of their innervation. In 16-day embryos treated by the a-toxin, the endplates revealed by the Koelle reaction are almost completely absent. The total content and specific activities of acetylcholinesterase and choline acetyltransferase in atrophic muscles are markedly reduced.Snake venom a-neurotoxins bind with a high affinity and a low reversibility to the cholinergic (nicotinic) receptor site (1-3).They have therefore been widely used to assay, characterize, and identify the protein that carries this site (see ref. 4).These neurotoxins can also be used to create a chronic block of neuromuscular transmission at the postsynaptic level and to analyze the consequences of this block in the differentiation, morphogenesis, and stability of a neuromuscular synapse.In this paper, we report on the cholinergic receptor sites in chick-embryonic muscles and on their evolution during development, in comparison to the appearance of choline acetyltransferase and acetylcholinesterase. Injection of the atoxin from Naja nigricollis at early stages of development causes a marked atrophy of skeletal muscles and of their innervation, accompanied by characteristic changes in their content of choline acetyltransferase and acqtylcholinesterase. MATERIALS AND METHODS[3H]a-Toxin. The al-isotoxin was purified from the venom of Naja nigricollis by the method of Boquet et al. (5) The stock solution contained 24 MM a-toxin (10.2 Ci/mmol); 72% of the molecules of a-toxin were active.Embryos. Chick embryos were obtained from fertilized eggs of a local strain and incubated at 380 at a relative humidity of 70-80%; 3-, 4-, 5-, 6-, 8-, 11-, 12-, 14-, 16-, 18-, and 21-dayold embryos were used. Muscles were dissected under a stereomicroscope and quickly frozen; most samples were lyophilized and stored at -45°. With 3-to 6-day-old embryos, assays were made on posterior limb buds; from the 8th day of incubation and after, the posterior muscles of the leg were used.The embryos were treated with a-toxin by three successive injections (the 3rd, 8th, and 12th day of incubation) in the yolk sac with a Hamilton syringe, through a small window in the

No abstract