Science
Humans Have Been Perfecting Avocados for 7,500 Years
Avocados are true superfoods: dense, buttery scoops of vitamins, fat and fiber, all in a hand-size package.
We worked for a long time to make them this way. According to a paper published Monday in the Proceedings of the National Academy of Sciences, people in what we today call Honduras made avocados a part of their diets at least 10,000 years ago and purposefully improved them starting more than 7,500 years ago — first by managing wild trees, and then by selectively planting new ones, to encourage thicker rinds and larger fruit.
This means fruit domestication at this site began thousands of years before the arrival of more commonly studied plants like maize.
“People were domesticating and cultivating their forests” long before they were planting crops in fields, said Amber VanDerwarker, a professor of anthropology at the University of California, Santa Barbara and an author of the paper.
Avocados first arose in central Mexico about 400,000 years ago. They were originally dispersed by megafauna: Giant ground sloths, elephantine gompotheres and burly toxodons all regularly gulped them down, choking-hazard-size pits and all. By the end of the Pleistocene epoch, around 13,000 years ago, megafauna had spread the oily fruits throughout Central and northern South America, and helped them diversify into at least three different species.
But the mass megafaunal extinction that ended the Pleistocene left the avocados stranded: Without animals big enough to eat them whole and spread their seeds, their range began to shrink. At this point, “humans stepped in,” said Doug Kennett, a professor of environmental archaeology also at the University of California, Santa Barbara and an author of the paper. These humans — who, without the megafauna, now needed new food sources — began cultivating the fruit, “saving avocados,” Dr. Kennett said.
For the new study, researchers focused on a site in western Honduras called El Gigante, an elevated cave that people began frequenting 11,000 years ago. Over generations of living and working there, humans left heaps of discarded squash seeds, maize kernels, agave leaves and much more. Archaeologists have been sifting through it all for about 20 years.
To learn about how people at El Gigante enjoyed avocados, researchers looked at dozens of their seeds found in this “long-term trash pile,” as well as thousands of rind fragments, Dr. VanDerwarker said. They used radiocarbon dating to put these scraps in chronological order, and measured the thicknesses of the rinds and the dimensions of the seeds.
Comparing seed and rind sizes over time allowed the team to trace how humans shaped the fruit. Early on, people were “just picking wild fruits from their trees as they need to,” and the trash was littered with cherry-size seeds and thin bits of rind, Dr. VanDerwarker said.
In layers from about 7,500 years ago, the seeds had become larger and the rinds more robust. This suggests that people were managing existing trees, pruning some branches and new fruits in order to encourage the remaining ones to grow bigger.
In layers from 4,500 years ago, seeds had reached apricot size and rind thickness had pushed beyond the plant’s natural variation — “an indicator that people had started saving seeds and planting their own trees,” Dr. VanDerwarker said. The arborculturalists favored large fruits, as well as hefty skins that helped with preservation and transport.
The study gives “new evidence for 10,000 years plus, probably, of avocado use,” said Tom Dillehay, a research professor at Vanderbilt University who was not involved with this particular study. He said he had found similar signs of longstanding avocado enjoyment in northern Peru; other evidence has been found in Mexico, Colombia and Panama. Dr. Dillehay predicts that as research continues, more sites, and more types of manipulated food plants, will be discovered.
The finding also continues an ongoing shake-up of the notion that food domestication began with animals and cereal grains. That early avocado growers were putting so much effort into their plants is “different than what was imagined even 10 or 15 years ago,” Dr. Kennett said.
While our concepts of plant husbandry come and go, some things are more timeless. One reason to want to cultivate a thick avocado rind is for ease of scooping, said Dr. VanDerwarker, inspiring other tasty imaginings: “I think people have probably been eating guacamole now for a good 10,000 years.”
Science
Scientists find a whale graveyard in the Indian Ocean that’s millions of years old
NEW YORK — Scientists have unearthed communities of marine life — including jellyfish, tubeworms and brittle stars — thriving on a whale graveyard that is millions of years old.
These graveyards form when whale carcasses fall to the sea floor, becoming a sustaining snack for nearby critters. This one, located up to 23,000 feet below the surface of the southeastern Indian Ocean, spans the largest area and is so far the deepest and oldest found.
A whale’s sheer size and the unique chemistry of its bones are the keys to forming these unique underwater neighborhoods, said Xikun Song, a biologist with the Chinese Academy of Sciences’ Institute of Deep-sea Science and Engineering.
“At the same time, the very nature of the deep ocean makes these sites exceptionally difficult for scientists to locate,” Song, who was involved with the latest find, wrote in an email.
Researchers explored the remains during multiple deep-sea submersible trips in 2023, collecting samples and mapping the extent of the necropolis. They found five carcass sites and fossils, including skulls belonging to beaked and baleen whales. The oldest bones date back 5.3 million years.
Feeding and living on the carcasses were myriad creatures, large and small, including sea cucumbers, squat lobsters and saltwater clams. Many of them are likely species that have never been documented, according to findings published Wednesday in the journal Nature.
“The potential number of specimens is just astounding,” said paleontologist Stephen Godfrey with the Calvert Marine Museum in Maryland, who wasn’t involved in the research.
Many factors likely conspired to preserve the bones for millions of years, according to the study authors. They’re dense enough to outlast attacks from bone-eating worms, and located deep enough in the ocean to avoid getting buried by dust and loose particles. The bones also were coated with a light layer of minerals from the surrounding seawater, which may have prevented them from degrading.
Why did so many whales die here? Maybe they were already living in the area and died of natural causes. A few could have perished from exhaustion or illness caused by deep-sea diving. The area’s shape, akin to the letter V, could also have funneled the remains to their resting spot, the authors wrote.
Such discoveries are important because they clue scientists into the vibrant communities that find a way to live even in remote, hard-to-reach environments.
Studying the whale graveyards “is important for understanding how life can adapt to such extreme conditions, not only due to the lack of light and oxygen but also to the incredibly high pressure,” said study co-author and paleontologist Giovanni Bianucci with the University of Pisa in Italy in an email.
Ramakrishnan writes for The Associated Press.
The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education and the Robert Wood Johnson Foundation.
Science
El Niño turns crumbling California pier into climate battleground over what to save — and who pays
As a historic El Niño supercharges the Pacific Ocean and San Francisco experiences record high seasonal sea levels, the latest structural casualty of intense wave action is prompting Bay Area politicians to call for help from the state and federal governments.
They want to rebuild a concrete pier shut down this month after officials deemed it unsafe because of cracking from decades of pounding surf and storms.
As waves crashed against the derelict structure Monday morning, U.S. Rep. Sam Liccardo (D-San José) held a news conference and asked the federal government to follow through on $50 million in climate resilience funding promised by the Biden administration but terminated by the Trump administration in 2025.
The city of Pacifica had been on the shortlist for the Building Resilient Infrastructure and Communities program, managed through FEMA. California and 22 other states successfully sued to reinstate the program, but the funding has yet to be allocated.
Liccardo also asked for nearly $1 million in promised funds from the National Oceanic and Atmospheric Administration for a handrail project on the pier and an additional $9 million to protect coastal bluffs.
Coastlines are already being buffeted and inundated by rising seas. With the closed-off Pacifica Municipal Pier in the background, local politicians and community members said they’re on the front lines and want to rebuild.
“Pacifica is ground zero for coastal resilience,” said state Sen. Josh Becker (D-Menlo Park), as he asked Gov. Gavin Newsom to declare a state of emergency and “help us fix this pier and help this community recover again.”
“This is very much a reminder that an ounce of prevention is worth a pound of cure,” he said, noting that previous attempts for funding went unheeded. “We cannot wait until infrastructure fails before we invest in protecting it.”
As climate change starts to become expensive, it prompts questions about what to protect and what to abandon.
Chad Nelson, chief executive of the Surfrider Foundation, a coastal environmental advocacy organization, said city piers provide coastal access to people who can’t swim or walk on the beach; they are often popular fishing spots and tend to serve a broad swath of their communities.
On the flip side, he said, they keep getting beat up by the ocean and costing taxpayers millions of dollars to repair or replace.
In Santa Cruz, a public wharf damaged by storms in 2024 recently reopened after $1.3 million in repairs. In Capitola, a storm-damaged wharf reopened earlier this year after $10 million had been sunk into repairs. The city is now considering building an open-air restaurant, public bathrooms, a bait shop and a boat launch.
“I think the larger question is: Are we subsidizing bad responses to problems that we know are going to persist?” he said, responding to a question about infrastructure that won’t last.
Charles Lester, director of the Ocean and Coastal Policy Center at UC Santa Barbara, agreed with Nelson that it’s important to distinguish public from private benefits.
“There’s a bit of a difference between a public recreational pier, for example, and your private development that’s going to impact the beach,” he said.
And at some point, he said, we have to acknowledge things are only going to get worse.
In a white paper authored by Lester and Nelson, the two described the coming El Niño as a “reckoning” for the California coast.
El Niños result in larger waves, elevated sea levels and powerful storms — “predictable signature(s) of a climate pattern that returns every two to seven years and is expected, as the planet warms, to intensify,” they wrote.
Wave energy along the shore can run 50% above average during an El Niño, while sea levels can climb 6 to 12 inches — flooding coastal homes, roads and infrastructure. Coastal erosion increases by more than 69% during extreme El Niño events, according to the U.S. Geological Survey.
During the 1997-98 El Niño, seven Pacifica seaside houses were condemned after powerful waves and storms made them unsafe and irreparable. Seventeen people in the state died as a result of the historic flooding and storms.
The funding requests for the pier also come as San Francisco sees its highest summer water levels ever. On Saturday, the National Weather Service recorded levels 1.83 feet above normal high tide. Early Monday morning, the popular Pier 14 along the city’s Embarcadero waterfront was submerged.
High surf along the coast killed a young girl in Laguna Beach, and hundreds of people have been rescued at Newport Beach. Water stranded a hiker along the cliffs of San Francisco’s Presidio — requiring a seven-hour rescue mission that ultimately left the hiker and a rescuer injured as the waves crashed them into the rocks.
“This stretch of coast has been a continuous coastal emergency declaration for almost 10 years due to the repeat damage of storms in recent El Niño years,” the mayor of Pacifica, Christine Boles, said.
Pacifica has been planning for climate change for years, she said. But climate change is outstripping those efforts, and without financial and regulatory support from the federal and state governments, the battle will be all but lost.
Science
Californian is infected with rare tick-borne illness. What to know about the deadly bacteria
A Northern Californian has been confirmed as the fourth-ever person diagnosed with a newly recognized and rare tick-borne disease that causes symptoms similar to Rocky Mountain spotted fever.
The California Department of Public Health confirmed the latest case of Rickettsia lanei bacteria in a patient who was diagnosed in April of this year. Two other California cases were reported in 2004 and 2023.
Public health officials told The Times that the infected person “was seriously ill, hospitalized and has since been discharged and is recovering.”
It is unclear how long the person was in the hospital or what their symptoms were. The state agency said it could not disclose the home county of the person but confirmed the infected person lived and worked in Northern California.
Rickettsia lanei comes from the spotted fever group Rickettsia, bacteria transmitted to humans from the bite of an infected tick.
In California three types of ticks — the American dog tick (Dermacentor similis), the Pacific Coast tick (Dermacentor occidentalis) and the brown dog tick (Rhipicephalus sanguineus) — can transmit the bacteria that cause Rocky Mountain spotted fever in humans and dogs, according to the California Department of Public Health.
Symptoms of Rocky Mountain spotted fever can range from fever and a rash to long-term effects that include damage to internal organs or neurological disorders.
The tick-borne disease has been spreading globally since the early 2000s, most notably in Mexico and Brazil, with reported fatality rates that can exceed 50%, according to a study published by UC Davis.
What is Rickettsia lanei?
Rickettsia lanei bacteria were identified this year in a few Pacific Coast ticks, including a tick in Contra Costa County, according to SFGate, where the latest case was first reported in April.
The new bacterium was added to the list of potentially transmittable pathogens in 2024 by the state public health department after its severe symptoms were studied in two cases of infected men nearly 20 years apart, according to a report published in the Centers for Disease Control and Prevention Emerging and Infectious Diseases journal.
“Sustained investment in public health has enabled development of the advanced molecular tools that detected these infections,” the California Department of Public Health said in a statement to The Times.
According to the report, both men fell ill after spending time outdoors, one playing golf at five courses in Alameda and Contra Costa counties within 14 days of the onset of his symptoms. This first patient had fever, headaches, muscle pain, malaise, loss of appetite, diarrhea and abdominal pain, among other symptoms. His condition worsened on his third day in the hospital, according to the report. The man was ultimately in the hospital for 22 days, including 11 in the intensive care unit with a primary diagnosis of rocky mountain spotted fever and a secondary diagnosis of acute kidney injury.
The other infected person had visited and camped at a county park and state beach in San Mateo and Marin counties. The second man reported a five-day history of headaches, vomiting, light sensitivity, neck pain and confusion, according to the report. On the third day of hospitalization, the man became comatose and was intubated, the report stated. After 13 days, he was discharged with a primary diagnosis of severe Rickettsia.
Researchers have known about Rickettsia lanei since 2018 when it was detected in rabbit ticks in Sonoma County, but they didn’t know its potential harm to humans because the rabbit tick rarely bites people.
“The Pacific Coast tick, which bites humans more frequently, may occasionally acquire the organism from an infected rabbit, which is the most likely route for the rare human infections that have been identified,” the state health agency said.
Should I be worried about contracting Rickettsia lanei?
Human infections are rare but could be underreported because Rickettsia lanei symptoms are very similar to those of rocky mountain spotted fever, said Janet Foley, veterinarian and disease ecologist at UC Davis.
“I think it’s so new that I don’t know if anybody’s really gotten a grant to study it or put it under a microscope,” Foley said.
Rickettsia lanei bacteria cases could also have gone undetected for so long because some cases were not severe, she said.
Foley said Californians should be aware of Rickettsia lanei and take precautions against tick bites.
How to keep disease-carrying ticks at bay
The best way to avoid ticks and tick bites is to be vigilant in your surroundings, Foley said, noting that ticks can transmit other diseases such as Lyme disease.
To keep a disease-carrying tick at bay, Foley recommends:
- Covering up your arms and legs when outdoors by wearing pants and long-sleeved shirts.
- Staying out of the grass where a tick can latch onto your clothing. Instead stay on a cleared path.
- Wearing light-colored clothing so it’s easier to spot a tick if one jumps on you.
- After an outdoor activity, take off your clothes, toss them in the wash and take a shower.
- If your dog goes with you for outdoor activities, give it a bath and then apply tick medication.
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