I can't remember when it was that I realised I have a serious problem where Heidi Klum is concerned. Was it when she posted a self-deprecating video on Instagram that showed her being driven to the Emmys? She was lying flat on the back seat to ensure she arrived in her strapless silver gown wrinkle-free. It was funny. A bit daft.
I couldn't imagine many A-listers publicly admitting to doing the same thing.
![Gigi Hadid on the set of a photoshoot in New York.](/web/20170122095532im_/http://www.smh.com.au/content/dam/images/g/t/u/b/w/o/image.related.articleLeadwide.620x349.gtubom.png/1485046727770.jpg)
Or was it when she wished her father a happy birthday by putting up a photo of herself with him in the 1980s? Her father was sporting a heavy beard and retro, sepia-tinted spectacles and looked a bit like the man from the illustrated guide The Joy of Sex. Klum was a fresh-faced, slightly nerdy-looking teenager. Again, it was an entirely unselfconscious post and it made me like her for sharing it.
Or was it, perhaps, when she shared a Face Swap she'd done with chat-show host Jimmy Fallon that ended up looking like a cross between a cyborg and a demented drag queen?
I don't know. I just know that I follow Heidi Klum's Instagram posts with something akin to devotion.
I like her style: simultaneously sexy but classy, with an ingrained sense of fun. I admire the fact that, as a 43-year-old mother of four, she looks considerably hotter than most 20-somethings.
I like her captions and their Germanic straightforwardness and the sense she never takes herself too seriously. I even like that she used to be married to the singer Seal, whose song Kiss from a Rose was the soundtrack to every teenage disco I ever went to.
Have I met her? Of course not. It's just that I'm in the full grip of an Insta-crush. I am a moderately sensible, not wholly stupid, professional woman in her 30s. I'm grown-up enough to know better. And yet I've developed a mild obsession with people on Instagram I don't actually know.
Heidi Klum is just the start of it. I follow Gigi Hadid because, even though I'm never going to be a supermodel myself, it's kind of nice to know what one of them does all day (hang out with Kendall Jenner and look great in leather trousers, mostly). I even follow the odd Kardashian because I'm endlessly hypnotised by how their faces seem to have been moulded specifically for the act of selfie-taking.
The people on whom I have an Instacrush don't have to be famous. I follow the occasional professional yoga poser so that I can look at their Warrior II stances on Mauritian beaches at sunset and convince myself that I look as good as they do when I'm sweating it out in a baggy T-shirt and overstretched leggings.
A friend of mine follows a mother who sends her children to the same school, specifically so she can ogle her interior decor and steal her style secrets. My friend has begun buying the same jewellery as this woman (bracelets with pompoms are, apparently, Her Thing).
At Halloween, this mother posted a photo of elaborately carved pumpkin lanterns, sending my friend spiralling into an existential crisis. "She's so good at everything," she said, half-appalled, half-admiring. "I just … love her. Is that weird? It's weird, isn't it?"
I'm fascinated by which photo filters people choose. Former Made in Chelsea star Millie Mackintosh always seems to go for the warm tones of Valencia, which suggests a sunny disposition and a capacity for looking on the bright side. The designer Donatella Versace often picks black and white, which hints at a woman of a certain age who understands the benefits of flattering light.
Whenever I log on to Instagram, I like to keep tabs on these people. I like to see what they're wearing or laugh at the jokes they're making or assess their household furnishings. Occasionally I will admire the quality of their photographic composition.
I never actually "like" anything they post because I'm too nervous and because I want to play it cool. Also, the chances are that they wouldn't notice me among the 450,000 other heart buttons that have been pressed in the time I've been thinking about it. The only thing worse than not being acknowledged by the object of my Instagram affections is not being acknowledged when you've acknowledged them first.
So, from where does this one-way fascination stem? Partly, it's that I like the idea of knowing things about someone's life without fully knowing them. There's none of that boring business of having to find time to meet for coffee and talk about school sports days or who's going to win The Apprentice.
I suppose the closest equivalent is those (often same-sex) crushes I had on people in the years ahead of me at school, who offered a thrilling mix of closeness and unobtainability. Instacrushes, too, seem both otherworldly and intimate. They exist in a separate dimension and, at the same time, offer glimpses into supposedly "real" lives.
The scientific explanation for my mildly unhinged feelings towards the Instagram feeds of Klum, Hadid et al stems from an evolutionary tendency to try to ape other people's success. This makes me feel slightly better about myself because, if it's evolution, presumably I can't help it.
According to Jamie Tehrani, an anthropologist at Durham University, England, humans have adapted to copy the traits of successful people.
Our ancestors, for instance, might have watched a particularly successful hunter-gatherer and tried to carve their arrowheads in the same way to guarantee the same result. In the modern world, celebrities embody this idea of prestige, a form of social status that is based on the respect and admiration of members of one's community.
So instead of carving an arrowhead, I might log on to Instagram and see Beyoncé wearing shoes I want to buy. She's successful and popular, the subconscious reasoning goes, therefore I want to be more like her by copying her behaviour. (Also, let's be honest, I might just like her shoes.)
Fame is a powerful cultural magnet," says Tehrani. "As a hyper-social species, we acquire the bulk of our knowledge, ideas and skills by copying others, rather than through individual trial and error." Of course, sometimes this constant assessment of our own lives in comparison to other, richer, more famous people can have negative side-effects. If I'm feeling premenstrual and bloated and am loafing around in tracksuit bottoms eating a chocolate bar, I'm unlikely to be uplifted by Kylie Jenner's Instagram feed advertising her latest lip-care line.
But, by and large, I get an enormous amount of positivity from my Instacrushes. In an age where so much celebrity media coverage is designed to pull other women down, it's nice to feel I actually like the people I follow. I want them to look good, not be condemned to a worst-dressed list after a Met Gala.
Glenn Geher, a professor of psychology at the State University of New York, believes that our Instacrushes can be positive markers of developed social behaviour. Liking someone's posts on Instagram, and the possibility that your photos will be liked back, he writes in Psychology Today, leads to an understanding of "reciprocal altruism … we learn how to develop important relationships with others that are mutually beneficial."
I'm not sure how mutually beneficial Heidi Klum finds our Instagram relationship, given that she doesn't actually know it exists, but there's no time to worry about that right now. She's just posted a video of herself in the bath with rubber ducks and INXS playing in the background – and I'm sorry, but I have to watch it immediately. You understand.
TOP FIVE INSTA-CRUSHES
GIGI HADID @gigihadid
I love her Insta feistiness. When she faced criticism for looking "too curvaceous", she posted: "Yes, I have boobs, I have abs, I have a butt, I have thighs … If I didn't have the body I do, I wouldn't have the career I do … I'm proud of it." GO GIGI!
PHOEBE DAHL @phoebe
Designer and Roald Dahl's granddaughter, Phoebe is possibly the coolest woman on the planet. She runs Faircloth & Supply, a clothing line aiming to empower women. Follow her for achingly hip behind-thescenes fashion shoots.
SOLANGE KNOWLES @saintrecords
The lesser-known Knowles sibling specialises in arty snapshots. She has an eye for the beautiful tiny details of everyday life and a delightful, if eccentric, liking for photos of tables in empty rooms.
HEIDI KLUM @heidiklum
The Project Runway host and former model is funny, irreverent and stylish. She never takes herself too seriously, as evidenced by her penchant for unflattering Face Swaps and obsession with over-the-top Halloween costumes.
MICHELLE OBAMA @michelleobama
Because nothing brightens up my day as much as a picture of Michelle hugging someone on Instagram. (Also, you get adorable shots of Barack Obama thrown in for free.) We'll wait and see how Melania Trump's Twitter feed turns ou