We generated genome-wide data from 69 Europeans who lived between 8,000-3,000 years ago by enriching ancient DNA libraries for a target set of almost four hundred thousand polymorphisms. Enrichment of these positions decreases the sequencing required for genome-wide ancient DNA analysis by a median of around 250-fold, allowing us to study an order of magnitude more individuals than previous studies1–8 and to obtain new insights about the past. We show that the populations of western and far eastern Europe followed opposite trajectories between 8,000-5,000 years ago. At the beginning of the Neolithic period in Europe, ~8,000-7,000 years ago, closely related groups of early farmers appeared in Germany, Hungary, and Spain, different from indigenous hunter-gatherers, whereas Russia was inhabited by a distinctive population of hunter-gatherers with high affinity to a ~24,000 year old Siberian6. By ~6,000-5,000 years ago, a resurgence of hunter-gatherer ancestry had occurred throughout much of Europe, but in Russia, the Yamnaya steppe herders of this time were descended not only from the preceding eastern European hunter-gatherers, but from a population of Near Eastern ancestry. Western and Eastern Europe came into contact ~4,500 years ago, as the Late Neolithic Corded Ware people from Germany traced ~3/4 of their ancestry to the Yamnaya, documenting a massive migration into the heartland of Europe from its eastern periphery. This steppe ancestry persisted in all sampled central Europeans until at least ~3,000 years ago, and is ubiquitous in present-day Europeans. These results provide support for the theory of a steppe origin9 of at least some of the Indo-European languages of Europe.

Bell Beaker pottery spread across western and central Europe beginning around 2750 BCE before disappearing between 2200–1800 BCE. The mechanism of its expansion is a topic of long-standing debate, with support for both cultural diffusion and human migration. We present new genome-wide ancient DNA data from 170 Neolithic, Copper Age and Bronze Age Europeans, including 100 Beaker-associated individuals. In contrast to the Corded Ware Complex, which has previously been identified as arriving in central Europe following migration from the east, we observe limited genetic affinity between Iberian and central European Beaker Complex-associated individuals, and thus exclude migration as a significant mechanism of spread between these two regions. However, human migration did have an important role in the further dissemination of the Beaker Complex, which we document most clearly in Britain using data from 80 newly reported individuals dating to 3900–1200 BCE. British Neolithic farmers were genetically similar to contemporary populations in continental Europe and in particular to Neolithic Iberians, suggesting that a portion of the farmer ancestry in Britain came from the Mediterranean rather than the Danubian route of farming expansion. Beginning with the Beaker period, and continuing through the Bronze Age, all British individuals harboured high proportions of Steppe ancestry and were genetically closely related to Beaker-associated individuals from the Lower Rhine area. We use these observations to show that the spread of the Beaker Complex to Britain was mediated by migration from the continent that replaced >90% of Britain’s Neolithic gene pool within a few hundred years, continuing the process that brought Steppe ancestry into central and northern Europe 400 years earlier.

En el presente trabajo se analizan las distintas características que definen la decisión de estudiar Medicina. A través de una encuesta respondida por los estudiantes de segundo curso de Medicina se ha evaluado el momento de la decisión, los factores que han influido en la misma, los motivos por los que se ha elegido y el patrón de selección. Se presenta un análisis descriptivo de las variables indicadas y de la relación existente entre ellas, así como de la posible influencia del sexo en cada una. Entre los resultados obtenidos se observa que un gran porcentaje de estudiantes toman la decisión de estudiar Medicina antes que el resto de población preuniversitaria opta por la carrera a estudiar. Entre los estudiantes de Medicina, los que se deciden antes presentan diferencias significativas respecto a los factores de influencia, los motivos de la decisión y el patrón de selección. Por otro lado, se encuentra que los principales motivos por los que se elige esta carrera son los de tipo altruista y humanitario. Las mujeres presentan diferencias respecto a la especialidad que les gustaría hacer y en ellas los motivos instrumentales son significativamente inferiores respecto a los varones. En conclusión, los estudiantes de Medicina presentan un alto grado de vocación social, que se ha visto incluso reforzada por la masiva incorporación de la mujer a esta carrera.Palabras clave: carrera de Medicina, estudiantes de Medicina, elección, factores de influencia, motivos, patrones de selección y sexo.

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No abstract

En el presente trabajo se analizan las distintas características que definen la decisión de estudiar Medicina. A través de una encuesta respondida por los estudiantes de segundo curso de Medicina se ha evaluado el momento de la decisión, los factores que han influido en la misma, los motivos por los que se ha elegido y el patrón de selección. Se presenta un análisis descriptivo de las variables indicadas y de la relación existente entre ellas, así como de la posible influencia del sexo en cada una. Entre los resultados obtenidos se observa que un gran porcentaje de estudiantes toman la decisión de estudiar Medicina antes que el resto de población preuniversitaria opta por la carrera a estudiar. Entre los estudiantes de Medicina, los que se deciden antes presentan diferencias significativas respecto a los factores de influencia, los motivos de la decisión y el patrón de selección. Por otro lado, se encuentra que los principales motivos por los que se elige esta carrera son los de tipo altruista y humanitario. Las mujeres presentan diferencias respecto a la especialidad que les gustaría hacer y en ellas los motivos instrumentales son significativamente inferiores respecto a los varones. En conclusión, los estudiantes de Medicina presentan un alto grado de vocación social, que se ha visto incluso reforzada por la masiva incorporación de la mujer a esta carrera.Palabras clave: carrera de Medicina, estudiantes de Medicina, elección, factores de influencia, motivos, patrones de selección y sexo.

This corrects the article DOI: 10.1038/nature25738.

The index Whittaker convolution operator, recently introduced by the authors, gives rise to a convolution measure algebra having the property that the convolution of probability measures is a probability measure. In this paper, we introduce the class of Lévy processes with respect to the index Whittaker convolution and study their basic properties. We prove that the square root of the Shiryaev process belongs to our family of Lévy process, and this is shown to yield a martingale characterization of the Shiryaev process analogous to Lévy's characterization of Brownian motion.Our results demonstrate that a nice theory of Lévy processes with respect to generalized convolutions can be developed even if the usual compactness assumption on the support of the convolution fails, shedding light into the connection between the properties of the convolution algebra and the nature of the singularities of the associated differential operator.