Almost a third of the UK's primary school teachers are 30 years old or younger, according to the latest figures, making it one of the youngest workforces in the world.
The 31% rate is well above the global average of 13 per cent, according to the Organisation for Economic Co-operation and Development's latest Education at a Glance study.
And the report said that in England statutory salaries for experienced and qualified teachers last year were 10% lower than in 2005, and in Scotland they were 3% lower.
The OECD said after 15 years' experience, UK teachers' salaries have increased "considerably", to the point where they are around or exceed the OECD average across all levels of education, except upper secondary education in Scotland.
But it added that this salary progression stops at or before 15 years, and wages at the top end of the scale "once more lag behind those in other OECD countries".
Last week, the Government announced plans to raise teacher starting salaries in England to £30,000 by September 2022.
A Department for Education spokesman said: "We want the brightest and the best young talent to be drawn to the teaching profession, and the quality of entrants remains at an all-time high, with 19% of the 2018/19 cohort holding a first-class degree, the highest in any of the last five years.
"These young teachers bring vibrancy, new ideas and energy to the classroom, creating an inspiring learning environment for young people."
He added that this school year, teachers and school leaders are due to get an above-inflation pay rise, with a 2.75% increase to the top and bottom of all pay ranges.
Geoff Barton, general secretary of the Association of School and College Leaders, said the average age of the teaching profession is young because the nation is "losing far too many teachers from the profession".
"The latest statistics show that a third of teachers in England leave within five years of qualifying. We then have to recruit new teachers on an industrial scale in order to replace them. This results in a haemorrhaging of experience and a younger workforce.
"One of the reasons for this high rate of churn is because the real value of teachers' pay has declined since 2011 as a result of Government-imposed pay austerity.
"It has made teachers' salaries less competitive in the graduate labour market and made it more difficult to retain teachers."
Mr Barton added that the Government's proposals on teachers' pay are welcome and the ASCL is waiting to see how the plans are introduced.
