Stone-tipped spears may indicate early human cognitive, social skills

August 26, 2014

Attaching a stone tip onto a wooden spear shaft was a significant innovation for early modern humans living around 500,000 years ago. However, it was also a costly behavior in terms of time and effort to collect, prepare and assemble the spear.

Because stone tips break more frequently than wooden spears, they require more frequent replacement and upkeep, and the fragility of a broken point could necessitate multiple thrusts to an angry animal. So, why did early hunters begin to use stone-tipped spears? Tipped and untipped spears Download Full Image

To learn if there was a “wounding” advantage between using a wooden spear or a stone-tipped spear, ASU postdoctoral researcher Jayne Wilkins, doctoral student Benjamin Schoville and coauthor Kyle Brown from the University of Cape Town, conducted controlled experiments using tipped and untipped spear replications, a calibrated crossbow and ballistics gelatin. The experiments looked at the size and shape of the “wound,” penetration depth and damage done by extraction of the spear.

Wilkins and Schoville are affiliated with the Institute of Human Origins, a research center of the ASU College of Liberal Arts and Sciences in the School of Human Evolution and Social Change.

Their experiments found that although tipped spears did not penetrate deeper than the untipped spears, as is commonly thought, the tipped spears create wider wound cavities. These wider wound cavities would have caused more debilitating tissue damage to internal organs of animals, making hunts more successful. This is one explanation for an evolutionary advantage for tipping a spear with a stone, an innovation that may have significantly impacted the evolution of human life-history.

"Putting a fragile stone tip on a spear is risky,” said Schoville, “but we show that there are serious rewards in terms of both the size and shape of the wound created that made this innovation extremely worthwhile during our evolution.”

The authors also posit that the manufacture of the stone-tipped spears may represent the origin of new cognitive and social development in our human ancestors. Working memory (the ability to hold attention to multiple tasks in order to collect, prepare and combine different kinds of raw materials into a weapon) and constructive memory (the ability to imagine and plan for future tasks) were mental capacities required for tipped-spear construction.

In addition, since a stone-tipped spear is a skill likely to have been learned by being passed from generation to generation through social or group learning, stone-tipped technology is evidence of the evolutionary impact of “cumulative culture.”

The flip side of this greater human cooperation is where groups and individuals are more likely to cooperate when others have very lethal weapons – a situation still in play today.

The study, “An Experimental Investigation of the Functional Hypothesis and Evolutionary Advantage of Stone-Tipped Spears,” will be published Aug. 27, 2014 in the open-access journal PLOS ONE, at

Julie Russ

Assistant director, Institute of Human Origins


NSF funds ASU, Caltech workshop on synthetic biology

August 26, 2014

One of the 25 best inventions in 2013, according to TIME magazine, was the brief “resurrection” of the gastric brooding frog, extinct since 1983. Biologists at the University of Newcastle in Australia implanted preserved nuclei – collected from the frogs in the 1970s and kept on ice – into the egg of another frog species. The eggs divided spontaneously and developed into an embryo. Though none of the embryos survived for long, the complete genetic material from the extinct frog was present.

The “de-extinction” of species is only one of the many potentially transformative outcomes that may result from the field of synthetic biology. Other researchers are working to develop renewable biofuels; crops that require less water and fertilizer; more efficient and greener processes to produce chemicals; and new therapeutics and diagnostics for a wide range of human illnesses, among other projects. David Guston, Jenny Dyck Brian, and Richard Murray Download Full Image

While on the surface, all of these projects seem beneficial to society, they also include the possibility of unintended negative consequences to the environment and human health. For example, in 2005 researchers recreated the Spanish Flu, a virus that killed an estimated 50 million people worldwide in 1918. The goal of the scientists – to study and understand the virus’s lethality – was noble, but it is not hard to imagine how this information in the wrong hands could lead to a bioterrorism event of horrific proportions. Furthermore, while most scientists agree that we’re far from the ability to create life from scratch, the ethics of manipulating life and funding research to get better at doing so are pertinent issues now.

To help figure out how to grapple with these issues, the National Science Foundation (NSF) has awarded $150,000 to David Guston and Jenny Dyck Brian of Arizona State University, along with Richard Murray of the California Institute of Technology (Caltech), Pasadena, to conduct a workshop to develop research agendas addressing the societal questions of synthetic biology.

A bigger-picture approach

One of the primary goals of the workshop is to take a preemptive, bigger-picture approach to the field of synthetic biology. “Frequently, social scientists and technologists will work in isolation, and technologists will not consider societal impact of their work until after the work has proceeded,” says Susanne von Bodman, NSF program director. “At the end of technology development, it sometimes becomes difficult to engage the public because the technology has already taken a certain path. We hope that the community, by meeting early in the development of the technology of synthetic biology, will be able to plan for how best to engage the public and deal with the societal aspects of the technology as it develops.”

The workshop aims to bring together a large segment of social scientists and humanists, along with natural scientists and engineers, working in synthetic biology. Three NSF directorates are co-funding the workshop: biology, engineering and social, behavioral and economic (SBE) sciences.

“We want to provide an opportunity for them to meet each other, discuss societally-focused research agendas and articulate compelling visions of what that research might be and how to get it done,” says David Guston, a professor in the School of Politics and Global Studies at ASU. He is also co-director of the Consortium for Science, Policy and Outcomes (CSPO) and director of the NSF-funded Center for Nanotechnology in Society at ASU (CNS-ASU), which has been a leader in building a capacity to anticipate a variety of futures for emerging technologies through developing a vision of anticipatory governance.

Workshop participants will examine what research suits synthetic biology in particular. “A research agenda on societal issues should be different for synthetic biology than for nanotechnology or geoengineering,” says Guston. “How and where synthetic biology is emerging geographically, who’s funding it, what the norms of the researchers who are on the technical side of the field are, and how they’re handling challenges all affect that agenda.”

Expanding and continuing the conversation

Workshop co-organizer Richard Murray, professor of control and dynamical systems and bioengineering at Caltech, has worked on developing artificial molecular programs. He notes that the synthetic biology community has been relatively proactive about engaging different groups and thinking about societal issues. He sites the Asilomar Conference on Recombinant DNA from 1975 and the Synthetic Biology 1.0 meeting held 2004, both of which addressed and incorporated societal issues.

“What’s been missing, or hasn’t been as present,” says Murray, “is broad engagement with the social scientists.”  Furthermore, because the field is expanding and part of it is becoming more of an engineering discipline, “it’s a good time to have another conversation to see whether there are new issues and things we should be thinking about that we’re not,” says Murray.

One current challenge is raising awareness of these issues with biological engineers. The workshop will be able to draw on lessons learned from the International Genetically Engineered Machines (iGEM) competition, which involves more than 1,000 primarily undergraduate students from around the world each year. “A big part of iGEM has increasingly been thinking about the standards of the practice and how to understand ethical, legal and safety issues. All iGEM teams have that as part of their projects,” says Murray, who is a faculty sponsor at Caltech. Members of ASU’s current iGEM team have been invited to the workshop.

Raising awareness with the public about synthetic biology is another challenge the workshop will consider. “The public is relatively unaware of what the possible benefits are, in part, because those benefits haven’t yet been developed to the point where people can say for sure they’re going to happen,” says Murray. “On the other side, people worry about creating life, and [whether] should humans do that, though we’re far from that.”

While a life form has made use of synthesized DNA, “it couldn’t be done without the original living organism or the DNA it was synthesized with from another living organism,” explains Murray. “But people hear about it and worry about whether you can go and engineer organisms arbitrarily. We want to make sure people understand what really can and can’t be done, and what people really want to be able to do and how it can be used for the benefit of society.”

The business side of synbio

The workshop will also look at how to address the potential implications of synthetic biology on the bioeconomy, the political landscape and sustainability. “We want to look at some of the fascinating and complex issues that tend to get left out of larger policy reports,” says Jenny Dyck Brian, Honors Faculty Fellow in Barrett, the Honors College, at ASU and the third organizer of the workshop. She is also affiliate faculty with CSPO, the W.P. Carey School of Business and the School of Life Sciences. Her research has addressed how companies consider ethics when funding potentially transformative technologies.

A report released in May by Allied Market Research forecasts the global synthetic biology market to reach $38.7 billion by 2020. “Companies like BP and ExxonMobil are investing millions and millions of dollars in this technology, and the UK has put it on their list as one of the top eight innovations,” says Brian. “Yet there are currently no synthetic biology products.”

Another policy consideration will be the shift to more open source development. “It goes against other models of scientific innovation, which heavily rely on patents,” says Brian.

The workshop will take place Nov. 4-6, at the Tempe Mission Palms hotel. While the workshop is by invitation only, a public website with background papers, interviews and videos will be available after the workshop.

The School of Politics and Global Studies, School of Life Sciences, Consortium for Science, Policy and Outcomes, and Center for Nanotechnology in Society are all research units in ASU's College of Liberal Arts and Sciences. 

Jennifer Pillen Banks

Communications program coordinator, Center for Nanotechnology in Society