Wenda Trevathan | New Mexico State University (original) (raw)

Papers by Wenda Trevathan

Evolution, medicine & public health, 2018

Cesarean section (surgical removal of a neonate through the maternal abdominal and uterine walls)... more Cesarean section (surgical removal of a neonate through the maternal abdominal and uterine walls) can be a life-saving medical intervention for both mothers and their newborns when vaginal delivery through the birth canal is impossible or dangerous. In recent years however, the rates of cesarean sections have increased in many countries far beyond the level of 10-15% recommended as optimal by the World Health Organization. These 'excess' cesarean sections carry a number of risks to both mothers and infants including complication from surgery for the mother and respiratory and immunological problems later in life for the infants. We argue that an evolutionary perspective on human childbirth suggests that many of these 'unnecessary' cesarean sections could be avoided if we considered the emotionally supportive social context in which childbirth has taken place for hundreds of thousands or perhaps even millions of years of human evolution. The insight that human childbirth is usually a cooperative, even social event in which women are attended by familiar, supportive family and friends suggests that the harsh clinical environment in which women often give birth in the developed world is not the best setting for dealing with the strong emotional forces that usually accompany labor and delivery. We argue that providing a secure, supportive environment for laboring mothers can reduce the rate of 'unnecessary' surgical deliveries.

Infant Behavior & Development, 2008

This study investigated the effects of adrenocortical functioning on infant learning during an em... more This study investigated the effects of adrenocortical functioning on infant learning during an emotionally challenging event (brief separation from mother). We also explored possible relationships between maternal sensitivity and both infant and maternal cortisol reactivity during the learning/maternal separation episode. 63 three-month-olds and their mothers were videotaped for a 10-min normal interaction period, and mother-infant behavioral synchrony was measured using Isabella and Belsky's (1991) coding scheme. The percentage of synchronous behaviors served as a measure of maternal sensitivity. Learning and short-term memory involved relating the infant's mother's voice with a moving colored block in a preferential looking paradigm. Infants whose cortisol increased during the session showed no learning or memory, infants whose cortisol declined appeared to learn and remember the association, while infants whose cortisol did not change evidenced learning, but not memory for the voice/object correspondence. Sensitivity and cortisol reactivity were correlated for mothers, but not for infants. Infant and maternal cortisol values for the first sampling period were highly correlated, but their cortisol reactivity values were uncorrelated, supporting the notion that infants and mothers have coordinated adrenocortical functioning systems when physically together, but become uncoordinated during a separation/learning event.

Evolutionary Anthropology, Jun 2, 2005

AND WENDA TREVATHAN. .. . adaptation to bipedal locomotion decreased the size of the bony birth-c... more AND WENDA TREVATHAN. .. . adaptation to bipedal locomotion decreased the size of the bony birth-canal at the same time that the exigencies of tool use selected for larger brains. This obstetrical dilemma was solved by delivery of the fetus at a much earlier stage of development. (Washburn'). .. . there can be no doubt that many of the obstetrical problems of Mrs. H. Sapiens are due to the combination of a narrower pelvis and a bigger head in the species. (Krogman 2) Although Washburn described it as as a "dilemma" and Krogman called it a "scar of human evolution," both authors recognized that the unique way that humans give birth is the result of a set of constraints imposed by several exclusively human attributes: bipedalism, a large brain, and "secondary altriciality," or the delivery of the infant in a helpless state. Although human birth has long been seen as a single compromise between locomotion and brain size, we now know that the particularly complex series of twists and turns that human babies make in the process of emerging from their mothers' birth canals is the result of a Karen Rosenberg is Associate Professor of Anthropology at the University of Delaware. She is a paleoanthropologist who has worked on fossils in Europe, the Near East and Eastern Asia. Her research interests are in the origin of modern humans and the evolution of modern human childbirth. Wenda Trevathan is Associate Professor of Anthropology at New Mexico State University. Her major research interests are the evolution of human female reproductive behavior, including sexuality, pregnancy, childbirth, and menopause. Her major publications include Human Birth; An Evolutionary Perspective and articles on menstrual synchrony, sexuality, and evolutionary medicine.

American Journal of Biological Anthropology

Compared to other primates, modern humans face high rates of maternal and neonatal morbidity and ... more Compared to other primates, modern humans face high rates of maternal and neonatal morbidity and mortality during childbirth. Since the early 20th century, this “difficulty” of human parturition has prompted numerous evolutionary explanations, typically assuming antagonistic selective forces acting on maternal and fetal traits, which has been termed the “obstetrical dilemma.” Recently, there has been a growing tendency among some anthropologists to question the difficulty of human childbirth and its evolutionary origin in an antagonistic selective regime. Partly, this stems from the motivation to combat increasing pathologization and overmedicalization of childbirth in industrialized countries. Some authors have argued that there is no obstetrical dilemma at all, and that the difficulty of childbirth mainly results from modern lifestyles and inappropriate and patriarchal obstetric practices. The failure of some studies to identify biomechanical and metabolic constraints on pelvic di...

Integrating Evolutionary Biology into Medical Education, 2019

Women’s reproductive health is often appropriately the focus of medical attention and interventio... more Women’s reproductive health is often appropriately the focus of medical attention and intervention in developed countries today. We argue, however, that clinical treatment can benefit from a greater understanding of the conditions under which female reproductive biology evolved. Reproductive factors such as timing of menarche and first reproduction, ovulatory cycles, levels of reproductive hormones, and fertility are shaped by local conditions, lived experiences of each woman, and evolutionary forces that have operated for many millennia on ancestral women. Aspects of our reproductive biology that we take for granted and think of as “natural” are actually products of our recent and current lifestyles—this includes monthly menstrual periods for much of women’s reproductive years for a total of as many as 450 cycles in their lifetimes. More typical of the human experience relevant to evolution is less frequent menstrual periods interrupted by pregnancy and several years of lactation f...

American Antiquity, 1996

The anatomical details of a birth scene depicted on Classic Mimbres (A.D. 1000-1150) bowls from s... more The anatomical details of a birth scene depicted on Classic Mimbres (A.D. 1000-1150) bowls from southwestern New Mexico can provide clues to gender relations in Classic Mimbres society. The scenes show an infant emerging facing forward (unusual in human birth) with its arms up (virtually unknown in human birth). These details suggest that the scene was painted by someone unfamiliar with the birthing process. Ethnographically, men rarely see human births. Thus, it is likely that the birth scene, and perhaps other Mimbres pottery designs, were painted by men.

Journal of Women & Aging, 2011

... I am appreciative of helpful feedback and responses to inquiries from Virginia Vitzthum, Cale... more ... I am appreciative of helpful feedback and responses to inquiries from Virginia Vitzthum, Caleb ''Tuck'' Finch, Kathryn Dettwyler, Chris Kuzawa, Sara Stinson, Mel Konner, and my ''consultants'' Jennie Lentz, Marcia Trevathan, and the students in my Anthropology of Reproduction ...

Evolution, medicine, and public health, Jan 10, 2014

Rising caesarean section rates worldwide Despite the World Health Organization's (WHO) recommenda... more Rising caesarean section rates worldwide Despite the World Health Organization's (WHO) recommendation that caesarean section (c-section) rates should not exceed 15% [1], the high rates in some countries are cause for concern. For example, Italy, China, Mexico and Brazil all have rates higher than 36% [2] with great variation within each nation. The need for c-section has probably increased for many reasons, including rising rates of obesity, diabetes and maternal age, but rates more than twice the WHO recommendation probably reflect more than medical necessity. Although the lives of millions of mothers and infants have been saved by c-section, surgical delivery is not without costs. Risks to mothers include haemorrhage, pulmonary embolism, sepsis and death [3] as well as compromised breastfeeding and bonding [4]. C-sections may carry risk for infants regarding respiratory, metabolic, gastrointestinal and immune function [5]. Finally, there is increasing evidence for epigenetic changes with c-section [6] suggesting that it may not be just the mother and infant who are affected by surgical deliveries, but there may be transgenerational effects.

The Biomedical & Life Sciences Collection, 2018

Anatomical record (Hoboken, N.J. : 2007), May 1, 2017

Birth mechanics in early hominins are often reconstructed based on cephalopelvic proportions, wit... more Birth mechanics in early hominins are often reconstructed based on cephalopelvic proportions, with little attention paid to neonatal shoulders. Here, we find that neonatal biacromial breadth can be estimated from adult clavicular length (R(2) = 0.80) in primates. Using this relationship and clavicular length from adult Australopithecus afarensis, we estimate biacromial breadth in neonatal australopiths. Combined with neonatal head dimensions, we reconstruct birth in A. afarensis (A.L. 288-1 or Lucy) and find that the most likely mechanism of birth in this early hominin was a semi-rotational oblique birth in which the head engaged and passed through the inlet transversely, but then rotated so that the head and shoulders remained perpendicular and progressed through the midplane and outlet oblique to the main axis of the female pelvis. Any other mechanism of birth, including asynclitic birth, would have resulted in either the head or the shoulders orthogonal to the short anteroposteri...

Practicing Anthropology, 1991

In this issue Clinton Burleson of New Mexico State University at Alamo gordo and Wenda Trevathan ... more In this issue Clinton Burleson of New Mexico State University at Alamo gordo and Wenda Trevathan of New Mexico State University at Las Cruces describe an example of an "expert system" called SkelMAP, to be used in helping students and professionals conduct skeletal analysis in both forensic and archaeological research situations. In both cases, it should be of great practical help to people working with skeletal materials.

The International Encyclopedia of Human Sexuality, 2015

Life history theory provides a way of viewing life course traits such as length of gestation, dur... more Life history theory provides a way of viewing life course traits such as length of gestation, duration of lactation, onset of puberty, and developmental state at birth through the lens of evolution. Given that energy for growing and reproducing is available in limited supply, life history theory argues that natural selection has shaped life history traits in ways that increase reproductive success. It helps predict what will be traded for what, under certain environmental conditions, including social and cultural circumstances, and enhances understanding of the human tradeoff of quality of offspring over quantity. Keywords: evolutionary tradeoffs; life history traits; reproduction