Welcome by CARTA Executive Co-Director, Pascal Gagneux. Opening remarks by Event Co-chair, Stephen Stearns.
Mismatch: Human Origins and Modern Disease
Friday, May 16, 2025Abstracts
Abstracts
Cancer is the origin of a novel tissue that attracts resources, spreads beyond boundaries, avoids normal controls, and escapes immunity. A novel tissue arises in the same way that bodies are built from nothing, by development. Cancer is normal development spun out of control. It is the great plasticity and power of development, without the overarching controls that guide normal development toward an integrated adult form. Instead, whenever a newly developed kind of tissue acquires the ability to survive, grow, and resist control, there is nothing to stop it. That may be why normal adult cells are often terminally differentiated into a restricted cellular program. And it may be why wound healing, which releases the restricted cellular program and powerfully plastic tissue remodeling, is so tightly regulated and, when dysregulated, so often associates with cancer. With regard to evolutionary history, humans develop differently from their ape ancestors, and their lifestyle causes them to suffer different kinds of tissue damage. Those differences in development and wound healing likely led to new aspects of cancer disease over human history.
Menstruation is the cyclical shedding of the endometrium triggered by falling progesterone levels. Menstruation is a rare trait found in less than 2% of mammals and likely evolved independently at least 4 times. Why do some mammals menstruate while most do not? The leading hypothesis is that menstruation occurs as a nonadaptive consequence of spontaneous decidualization of the endometrium, which evolved to increase biosensoring of embryo quality. While the trait of spontaneous decidualization (and as a byproduct, menstruation) was likely shaped by natural selection, menstruation also disposes women to conditions such as endometriosis, pre-menstrual syndrome, and bleeding disorders, especially in the contemporary context.
The rate of cancer and cancer malignancy differ greatly among mammalian species. The placental – maternal interface is also highly variable between placental mammals. Here I want to discuss recent advances that suggest that there is a causal connection between the evolution of placental biology and the biology and rate of cancer malignancy.
Cancer is a complex disease with different stages from the origin of the primary tumor to the establishment of secondary tumors in other organs than that of its origin. In this talk I will focus on the initial stages of malignancy, i.e. after the formation of a primary tumor and before the dissemination of cancer cells through the lymph vessels. This is the process of local invasion into the tumor surrounding stroma. This stage is the one that has inspired most of the comparisons between cancer and [invasive] placentation. I will present previously published work supporting the notion that the critical cell type in this process is the tumor associated fibroblast population explaining species differences in malignancy rate among species correlated with placental phenotype. Then I will present evidence that the gene expression evolution in uterine endometrial fibroblasts and skin fibroblasts is correlated, suggesting that evolutionary change in the uterus can lead to changes in the skin fibroblasts and vice versa. I like to end with some speculations how the evolutionary biology of placental implantation may be useful for translational efforts to make cancer less malignant for humans.
(no abstract)
(no abstract)
The essence of Being Human is the practice of Biocultural Reproduction (BCR). BCR is defined as the set of marriage and kinship based rules for extra-maternal cooperation in the production, feeding, and care of offspring. Human evolution theory needs to explain how people successfully combined a vastly extended period of offspring dependency and delayed reproduction with helpless newborns — with large heads and much body fat (even with problems giving birth) -- a short duration of breast-feeding, an adolescent growth spurt, and vigorous post-menopause valuable grandmothers. Are these characteristics a package or a mosaic?
Question and answer session with all speakers. Closing remarks by CARTA Executive Co-Director, Pascal Gagneux.
