Robin Dunbar, an anthropologist from England, has been studying and refining his theory on how large human networks can realistically get. Graphic by Miguel Tovar/University of Houston

You go to conferences; you network; you collaborate — all researchers and academics do. But do you need more than 150 contacts? Linkedin, Facebook, Twitter — all of these platforms open us up to the possibility of thousands of acquaintances, though fewer we would refer to as "friends."

Studying the primate brain

Robin Dunbar, an anthropologist from England, has been studying and refining his theory of the "Dunbar number" for 30 years. Dunbar became convinced that there was a ratio between brain sizes and group sizes through his studies of primates. "This ratio was mapped out using neuroimaging and observation of time spent on grooming, an important social behavior of primates. Dunbar concluded that the size, relative to the body, of the neocortex – the part of the brain associated with cognition and language – is linked to the size of a cohesive social group," wrote Christine Ro in a 2019 BBC.com Future article.

After the group reached approximately 150, it collapsed.

Your network

Is it true that humans based on their brain, and especially pre-frontal lobe size, are only able to connect in an intimate manner with around 150 other individuals? Defined as someone you would make plans to have a drink or coffee with if you bumped into them randomly on the street, Dunbar's claim is that it seems to be a consistent theme throughout history. Says the BBC: "This rule of 150 remains true for early hunter-gatherer societies as well as a surprising array of modern groupings: offices, communes, factories, residential campsites, military organizations, 11th Century English villages, even Christmas card lists."

The Dunbar number decreases by a "rule of three" where the next step down is the number 50 – those you consider "friends." Then about 15 in a closely knit circle, and four to six only in our familial or closest friend contacts.

Social media and COVID-19

"What determines these layers in real life, in the face-to-face world… is the frequency at which you see people," says Dunbar. "You're having to make a decision every day about how you invest what time you have available for social interaction, and that's limited." So, social media and COVID would seem to be game-changers for this theory.

Dunbar went on to study the process of "grooming" and light touch with astonishing results, which you can read about in the New Yorker. Basically, if a person has a face-to-face encounter with a friend, they are consequently able to withstand unpleasantness right afterwards (their hands stuck into a bucket of ice, for instance!) at a much higher rate.

"It makes sense that there's a finite number of friends most individuals can have," wrote Ro. "What's less clear is whether that capacity is being expanded, or contracted, by the ever-shifting ways people interact online …'It's extremely hard to cry on a virtual shoulder,' Dunbar deadpans."

And how has COVID changed Dunbar's theory? "While our culture has encouraged us to accumulate friends, both on- and offline, like points, the pandemic has laid bare the distinction between quantity and quality of connections," said a New York Times article. "There are those we've longed to see and those it's been a relief not to see."

The Big Idea

Many try to debunk Dunbar's number, by saying that primate and human brains differ and that the calculations are off. Robin Dunbar defends his theory thirty years after first proposing it in The Conversation.

The number of people you can just recognize according to Dunbar, is about 1,500, so you might want to keep that in mind if you are an extrovert and have an incredibly large network of collaborators – both online and offline.

University of Houston's central research department, the Division of Research, has about 100 members. But, your Linkedin network — check the number and see what it sits at. And if it's 600, ask yourself: do you really need that many contacts?

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This article originally appeared on the University of Houston's The Big Idea. Sarah Hill, the author of this piece, is the communications manager for the UH Division of Research.

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Houston startup funding surpasses $1B in 2025 despite national slowdown

by the numbers

Houston-area startups raised more than $1 billion in venture capital during the first half of 2025 — almost double the haul for the first half of last year.

According to the new PitchBook-NCVA Venture Monitor, Houston-area startups raised $417.2 million in the second quarter of this year, compared with $281 million during the same period last year. In the first quarter of 2025, local startups collected $607.5 million in venture capital, compared with $281 million during the same period a year earlier.

Based on those figures, Houston-area startups picked up slightly over $1 billion in VC during the first half of this year, compared with $535 million in the first half of 2024.

Nationally, startups gained almost $70 billion in VC in the second quarter, down 25 percent from the same period a year ago, the PitchBook-NCVA Venture Monitor says.

Nizar Tarhuni, executive vice president of research and market intelligence at PitchBook, explained that “the VC landscape continues to navigate a fragile recovery” and is constrained by economic uncertainty.

However, startups in certain sectors are poised to attract a great deal of attention and venture capital over the next several years, according to the report.

“Companies operating in AI, national security, defense tech, fintech, and crypto — sectors aligned with the administration’s priorities — are attracting disproportionately more investor interest, and this trend will likely continue throughout President Donald Trump’s term,” the report says.

The AI sector accounted for 64 percent of VC deal value in the first half of 2025, according to the report.

Houston space companies land $150M NASA contract for vehicles and robots

space simulations

Houston-based MacLean Engineering and Applied Technology Services LLC, known as METECS, has received a five-year contract from NASA to develop simulations and software services for space-based vehicles and robots, with a maximum value of $150 million.

Two other Houston-area companies, Tietronix Software Inc. and Vedo Systems LLC, were assigned as subcontractors for the award.

"This award is a strong testament to NASA’s continued trust in the quality of our work and their confidence in our ongoing support of the human spaceflight program," John MacLean, president of METECS said in a release.

According to NASA, the awardees are tasked with providing:

  • Simulation and software services for space-based vehicle models and robotic manipulator systems
  • Human biomechanical representations for analysis and development of countermeasure devices
  • Guidance, navigation, and control of space-based vehicles for all flight phases
  • Space-based vehicle on-board computer systems simulations of flight software systems
  • Astronomical object surface interaction simulation of space-based vehicles
  • Graphics support for simulation visualization and engineering analysis
  • Ground-based and onboarding systems to support human-in-the-loop training

The contract is called Simulations and Advanced Software Services II (SASS II), and begins in October. This is the second time METECS has received the SASS award. The first also ran for five years and launched in 2020, according to USASpending.gov.

METECS specializes in simulation, software, robotics and systems analysis. It has previously supported NASA programs, including Orion, EHP, HLS, Lunar Gateway and Artemis. It also serves the energy, agriculture, education and construction sectors.

Tietronix Software has won numerous awards from NASA. Most recently, it won the NASA JSC Exceptional Software Award (2017). Some of its other customers include Houston Independent School District, Baylor College of Medicine, DARPA and Houston Methodist.

Video Systems offers software for implementing human-rated, AI and autonomous systems, as well as engineering services to address the needs of spaceflight and defense. The company has previously worked with NASA and METECS, as well as Axiom Space and defense contractor Lockheed Martin.

The three companies are headquartered near NASA’s Johnson Space Center in Houston.