Yes, there is lots of ageism. If you don't have a Professorship in your 40s you're out, you'll rarely get a position. I've seen rare cases, but then you'd have

Yes, there is lots of ageism. If you don't have a Professorship in your 40s you're out, you'll rarely get a position. I've seen rare cases, but then you'd have to be really successful in your non-academic job - for example, upper levels of NGOs get recruited for highly visible professorships around NGOs, or business people get recruited for 'start up' professorships. These positions are usually 'handcrafted' for the business-person. But there's nothing below that, people won't jump into a mid-level academic career, those positions are full of 'regular' academics. Not just publications, but other reasons too - someone in their 40s has family and is not willing to work brutal hours and weekends required in many research labs, which someone in their 20s is more likely to accept. Of course it's worse if you're a mother.