Featured Research

from universities, journals, and other organizations

Ancient humans as major predators in marine food webs

February 22, 2012
Santa Fe Institute
Scientists have examined the feeding habits of human hunter-gatherers in the food webs on which they depended.

Although ecologists have studied food webs, the networks of who eats whom in the natural world, for decades, they have rarely asked how humans fit into the picture. Recent research by the Santa Fe Institute's Jennifer Dunne is the first to examine the detailed feeding habits of human hunter-gatherers in relation to other species.

Related Articles

By synthesizing 5,000 years of biological, archeological, ethnographic, and other data from marine systems in the North Pacific, Dunne and colleagues have characterized how humans fit into complex marine food webs, how they compare to other predators, and how their behaviors might have affected long-term ecosystem sustainability.

The results are surprising: Despite being "super-generalist" predators that fed on more species than other predators, the Aleut of Sanak Island, Alaska frequently switched among their many food sources, a flexibility that likely helped stabilize the entire ecosystem. This research provides a network-based perspective on how modern-day economic pressures might drive ecologically dysfunctional overharvesting of rare species and potential destabilization of whole food webs.

Dunne presented the work in a talk entitled "The Roles of Human Hunter-Gatherers in North Pacific Food Webs," at the American Association for the Advancement of Science meeting in Vancouver, B.C. Her talk was part of a symposium on "Historical Biocomplexity in the North Pacific Ocean: Lessons from the Past."

The Sanak Island data are the first highly resolved food webs that include humans, Dunne says. The data include more than 500 species and over 6,000 feeding links. The detail of the Sanak data raises the prospect of addressing many interesting questions in new ways, such as how humans compare to other species, and how they might have affected the sustainability of the system.

"Our analyses show that humans played special roles in the marine food webs," Dunne says. "As super-generalists, they fed on more kinds of species than most other predators." In the intertidal web, for example, the Aleut fed on 50 of 171 taxa. "They also were highly omnivorous," she says, "eating everything from kelp to sea otters."

While that may sound like a bad thing, it can be just the opposite, she explains. "We know that the Aleut lived on this island for thousands of years without other species going extinct. A super-generalist can co-exist with other species if it focuses on just a few of its possible prey at a time and switches prey regularly."

This is because generalists tend to focus on a preferred food source until it gets too difficult to find, and then they switch to something less preferred but easier to find. In the case of the Aleut, seasonal salmon may have been on the menu for awhile, followed by marine mammals, and when the weather got too stormy for hunting they could gather mussels and snails from the intertidal.

"This is a natural behavior for predators. It's stabilizing for the system because it allows populations to recover," Dunne says.

But food switching tends to be the opposite of what often happens in modern economic systems. Take blue-fin tuna, for instance. As the premium sushi tuna gets scarcer, its value goes up, and fishing becomes more profitable, leading to more, rather than less, pressure on tuna populations. This "increased rarity-higher value-more harvesting" cycle tends to drive species toward extinction and introduces dynamics that might destabilize the whole food web.

Dunne believes it is important to make sense of human impacts within an ecological framework, rather than treating humans as external to natural systems. "This type of network-based research provides new ways to understand human roles and impacts within complex ecosystems."

Story Source:

The above story is based on materials provided by Santa Fe Institute. Note: Materials may be edited for content and length.

Cite This Page:

Santa Fe Institute. "Ancient humans as major predators in marine food webs." ScienceDaily. ScienceDaily, 22 February 2012. <www.sciencedaily.com/releases/2012/02/120222132120.htm>.
Santa Fe Institute. (2012, February 22). Ancient humans as major predators in marine food webs. ScienceDaily. Retrieved March 2, 2015 from www.sciencedaily.com/releases/2012/02/120222132120.htm
Santa Fe Institute. "Ancient humans as major predators in marine food webs." ScienceDaily. www.sciencedaily.com/releases/2012/02/120222132120.htm (accessed March 2, 2015).

Share This

More From ScienceDaily

More Earth & Climate News

Monday, March 2, 2015

Featured Research

from universities, journals, and other organizations

Featured Videos

from AP, Reuters, AFP, and other news services

Solar Plane Passes New Test Ahead of World Tour

Solar Plane Passes New Test Ahead of World Tour

AFP (Mar. 2, 2015) A solar-powered plane made a third successful test flight in the United Arab Emirates on Monday ahead of a planned round-the-world tour to promote alternative energy. Duration: 01:05 Video provided by AFP
Powered by NewsLook.com
Heavy Toll as Australian Farmers Struggle Through Drought

Heavy Toll as Australian Farmers Struggle Through Drought

AFP (Mar. 2, 2015) Mounting debts, despair and forced repossessions are taking a heavy toll on farmers in parts of Australia suffering from its worst drought in 100 years. Duration: 02:16 Video provided by AFP
Powered by NewsLook.com
Whale-Watching Scientists Spot Baby Orca

Whale-Watching Scientists Spot Baby Orca

AP (Feb. 28, 2015) Researchers following endangered killer whales spotted a baby orca off the coast of Washington state, the third birth documented this winter but still leaving the population dangerously low. (Feb. 28) Video provided by AP
Powered by NewsLook.com
Bridge Collapses Due to Flooding in Bolivia

Bridge Collapses Due to Flooding in Bolivia

Reuters - News Video Online (Feb. 28, 2015) Heavy rain and flooding sweep through parts of Bolivia causing damage and leaves more than 2,000 people homeless. Sophia Soo reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.


Breaking News:

Strange & Offbeat Stories

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News


Free Subscriptions

Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile

Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?

Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins