Speakers

 Bernard Lahire

Research Director, CNRS, UMR 5283, Centre Max Weber Lyon

The bright and dark sides of secondary altriciality : Between altruism and domination

The concept of secondary altriciality was introduced in the 1950s by the swiss zoologist Adolf Portmann (1956), based on an interspecific comparison of ontogenetic development, and has been employed in paleoanthropology (Coqueugniot and Hublin 2005 ; Trevathan and Rosenberg 2016). It describes to the great prematurity of human babies, who are particularly vulnerable and undergo slow extra-uterine growth within socially structured environments, leading to a long period of dependence on adults.

This secondary altriciality extends even beyond childhood into a tertiary or even permanent altriciality (Lahire 2023). This is due, on the one hand, to the lengthening of the learning period in school-educated societies that require the transmission of an ever-increasingly massive and sophisticated accumulated culture, and on the other hand, to the strong division of labor that keeps all members of these societies in a state of permanent dependence on other more competent group members.

Furthermore, researchers have hypothesized that the high degree of dependence of infants during the first years of life has led to a form of cooperative breeding involving parents and allo-parents (Hrdy 2005; 2009). This situation has favored the reinforcement, and then extension of dispositions to mutual aid or altruism beyond adult-child relationships, distinguishing humans from other primates (Van Schaik and Burkhart 2010).

However, the necessity to dedicate time to feeding, caring for, monitoring, and protecting during the long childhood period has had a dual social consequence. Secondary altriciality generates, on one hand, a cooperative or altruistic push, representing the bright side of the phenomenon; and, on the other, a highly marked situation of dependence-domination, representing the dark side. This is what I endeavored to highkight in a recent book (Lahire 2023), which shows that much of the structure and development of human societies can only be understood from the perspective of the secondary altriciality and domination-dependence relationship between parents and children. In this sense, one can say that human childhood is the key to understanding many of the fundamental structures of human societies.

Secondary altriciality established a relationship of domination between parents and children (Elias 2010), a relational scheme that spread throughout the whole society: structuring relationships between the old and the young (with all forms of gerontocracy), elders and cadets (with the birthright), adults and minors, as well as between decesaed ancestors (or the traditions they embody) and the living who owe them respect, between anteriority (of things, people, lineages, clans, etc.) and posteriority, etc. This fundamental matrix also had major consequences from a magico-religious point of view (with dependence on spirits of ancestors or nature, or deities for protection in all dangerous life situations) and from the point of view of gender relations, where men are often considered as adults, elders, etc., compared to women who are regarded as minors, juniors or even children (Héritier 2010).

 Hélène Coqueugniot

Research Director, CNRS & Cumulating Study Director EPHE-PSL, UMR 6034 Archéosciences-Bordeaux

The Emergence of Secondary Altriciality in Human Evolution: Paleoanthropological Inquiry

The concepts of altriciality and precociality were developed in the early 19th century within ornithology by various authors under the latin terms of "altrices" and "praecoces" (Oken, 1816, 1821; Sundevall, 1835; Bonaparte, 1854; Owen, 1866). The first group refers to nidicolous species whose chicks are dependent and fed in the nest by parents for a certain period, whereas the second group refers to species whose chicks are autonomous from hatching. In 1866, Owen, and later Coues in 1870, extended these concepts to mammals, distinguishing those that "enter the world with all their senses" like the young of hoofed quadrupeds or cetaceans, from those "born weak, helpless, often blind and naked" like kittens, puppies, or rodents.

In April 1941, Swiss zoologist Adolf Portmann presented a communication to the Swiss Zoological Society posing a problem of comparative biology: the ontogenesis of humans compared to that of other anthropoid primates. Young primates belong to the group of mammals he called "Nestflüchter" or nidifugous (semantically equivalent to praecoces), while human babies, due to their prolonged dependence, would logically be "Nesthockers" or nidicolous (altrices). However, Portmann noted a paradox: human foetal growth is of the type seen in nidifugous mammals (senses are acquired at birth), whereas the postnatal period of the first year of human life is nidicolous (late acquisition of locomotion). Moreover, postnatal development during this first year of human life continues at an intrauterine-like pace, typical of nidifugous mammals. Portmann thus characterized this human singularity with the concept of "sekundären Nesthocker," which later spread under the term of secondary altriciality. According to him, the human gestation is abnormally short in comparison to mammals (it should actually last 21 months!) and the first postnatal year is a sort of "extrauterine spring" (“extrauterine Frühjahr”), which conditions human spirituality (“geistige”).

Understanding the timing of the acquisition of this secondary altriciality is therefore of paramount importance for palaeoanthropology to estimate when this developmental peculiarity emerges within the Hominin lineage. This communication will discuss the validity of existing or forthcoming fossil evidence on the issue of secondary altriciality in Homo genus. It can be deduced, between about 1.8 million years and 40.000 years ago, from juvenile remains of Homo erectus, Neanderthals, or early modern humans, by analysing their somatic and locomotor development rate in comparison with those of apes and modern humans. It can also be considered by examining the possibility of altruistic social behaviours in prehistoric societies towards adolescent or adult individuals, whose fossilized remains show physical, congenital, or acquired deficiencies that made them socially dependent, according to the new concept of ‘bioarchaeology of care’. Finally, it can be inferred by analysing prehistoric evidence such as burials and rock or portable art, materializing the development of a symbolic thought in prehistoric times that aligns with Portmann's notion of human spirituality, as a consequence of secondary altriciality.

 Jean-Jacques Hublin

Professor at the Collège de France, Director of the department of Human Evolution at the Max Planck Institute of Evolutionary Anthropology, Leipzig 

 [à paraître]

Michael Tomasello

Co-director of lthe Max Planck Institute of Evolutionary Anthropology, Director of the department of Developmental and Comparative Psychology at the Max Planck Institute, Leipzig

The Adaptive Origins of Uniquely Human Sociality

Humans possess some unique social-cognitive skills and motivations, involving such things as joint attention, cooperative and linguistic communication, dual-level collaboration and cultural learning. These are almost certainly adaptations for humans' especially complex sociocultural lives. The common assumption has been that these unique skills and motivations emerge in human infancy and early childhood as preparations for the challenges of adult life, for example, in collaborative foraging. In the current paper, I propose that the curiously early emergence of these skills in infancy––more than a decade before they are needed in adulthood––along with other pieces of evidence (e.g., almost exclusive use with adults not peers, ape-wide social-cognitive skills emerging earlier in humans than great apes) suggests that these skills represent ontogenetic adaptations to the unique (among apes) socio-ecological challenges that human infants face in their dependence on multiple adults in a regime of cooperative breeding and childcare.

 Sarah Blaffer Hrdy

Professor Emerita of Anthropology, University of California at Davis, 

Selectively altricial babies and their role in the evolution of Homo sapiens

No other ape displays as much interest in what others are intending and thinking as humans do (Tomasello 2019). And no other ape cares so much about conforming to the preferences of others and shaping what others think about them.  Even while remaining helpless and dependent on others for locomotion and provisioning far longer than other apes, otherwise altricial little humans are precociously at work reading and responding to the intentions and preferences of others, busy ingratiating themselves with them. Such youngsters are emotionally very different from other apes, preadapted  to mature into adults motivated to coordinate and cooperate with others. Over generations, brains selected for other-regarding emotions in infancy would have laid the groundwork for bipedal apes in the line leading to the genus Homo to develop unprecedented levels of inter-individual cooperation and food-sharing. As pointed out by  Burkart et al. (this conference) such shared provisioning would in turn facilitate growth and maintenance of the still larger, still more energetically expensive, brains characteristic of anatomically modern Homo sapiens. But long before the emergence of these sapient brains, Darwinian selection pressures among cooperatively breeding apes would have been favoring infants best adapted to what for apes (albeit not animals generally) was a novel mode of child-rearing (Hrdy and Burkart 2020).  Survival among such cooperatively breeding apes would have required infants to elicit care and provisioning from alloparents as well as parents.  In this presentation I seek to integrate new information from behavioral ecology, developmental psychology and social neuroscience in order to  highlight the role that infancy, a  life phase not ordinarily associated with sapient-grade mentalizing and strategic social evaluations, played in the evolution of anatomically modern human brains, including the precociously  activated and highly integrated human prefrontal cortex so critically important for processing social information and deciding how to respond.  

 Rayan Dequin

Doctorant en sociologie, UMR 5283, Centre Max Weber, Lyon

Elementary and advanced forms of the breakdown of parental care

In multicellular organisms that care for their offspring, parental behavior comes at a cost, with the human species ranking at the top of reproductive energy expenditure. Parental care often takes place in risky conditions: ecological (biotic and abiotic conditions), predation-related, or in unfavorable social conditions (harassment, child abduction or infanticide by dominants). Ensuring the survival of dependent offspring thus requires a great deal of attention and energy. In situations where the survival of the parents or part of their offspring is in jeopardy, it is not uncommon for the former to resort to abandonment or infanticide. These behaviors usually occur as early as possible, before the parents have “invested” too much in their offspring, the timing depending on the life history of each species.

In humans, articulate language, high levels of cooperation (reproductive, productive, redistributive) and cumulative culture (e.g. technical progress, social evolution, etc.), which are linked to secondary altriciality in our species, lead to major variations in social structures over time and space.

Thus, in our species as in the rest of the living world, the breakdown of parental care can be interpreted in terms of a binary classification: cost avoidance / profit. Depending on the social structure, these elementary forms can manifest themselves under a whole range of conditions: ecological and economic disaster, overpriced matrimonial services, sexual division of labor, the need for symbolic or material resources leading to human sacrifice or sale into slavery, each affecting its forms.

We shall see that when material and human resources are at stake, the life history of our species and the technical and social characteristics of human groups constrain the variation of infanticidal patterns.

 Judith Burkart

Research Director, Department of Evolutionary Anthropology, University of Zurich, Evolutionary Cognition  Group, Zurich

A CB-first model of human altriciality, sociality, and brain size evolution

Despite many similarities, several traits clearly set humans apart from other great apes, among others secondary altriciality, big brains, precocial social development, and extensive allomaternal care or cooperative breeding (CB). Comparative work over the last decades has significantly advanced our understanding of how these traits are linked. In this contribution, we review this evidence and suggest that an early adoption of extensive allomaternal care during human evolution, i.e. a CB-first model, best accommodates the available evidence.

We first consider the very tight link between a slow life-history and large brain size. We argue that the very large energy costs of a human-like brain size has major implications  for life history  that can only be sustained once a cooperative breeding system is in place, because otherwise demographic viability cannot be reached. Second, this system must have been in place before our secondary altriciality evolved as a result of energetic and/or anatomical constraints  that forced human mothers to give birth when the offspring has reached only ca 25% of adult brain size,  to immatures unable to cling to their mother and making the latter even more depending of help because their hands could not be used simultaneously to hold the baby and efficiently forage enough for themselves and their costly offspring. Third, our unusually early weaning relative to great apes, incongruent with our overall slower development, could only evolve when the extensive food sharing with offspring associated with CB was in place.

Next we turn to the old idea that it is in particular the period spent out of utero in the first year of life that plays a crucial role for the early socio-cognitive development because the still massively growing brain receives more social inputs. We challenge this idea based on data of healthy premature babies who grow up in intact family environments: despite having several weeks of additional social input available, their socio-cognitive outcome at 3 and 6 months is not superior compared to at-term or late born control infants; in fact, it is rather worse. We therefore propose to move away from a focus on punctual markers of altriciality, such as % of brain size available at birth, toward the neurodevelopmental pace of brain growth trajectories and brain differentiation relative to a broader set of developmental markers. By adopting this perspective for humans and marmosets, we are able to highlight how critical life events, including those unique to cooperatively breeding species (e.g. turning from being a recipient to becoming a provider of help), occur during key periods of brain differentiation and thus contribute to explaining the prosocial phenotype characteristic of both humans and marmosets. Finally we end by highlighting new approaches that will enable further tests of the CB-first model.