The early age for first period is associated with many factors such as higher socio-economic status, obesity, nutritional status and general health
England battled tenaciously to try and force an unlikely draw on the final day but Australia eventually bowled them out for 197 to take a 2-1 lead to the Oval and ensure that even a series draw would mean they retain the urn.
Former captain Smith, who has endured boos from the home crowds for his role in last year's ball-tampering scandal but has responded by piling up 671 runs in five innings, said it was incredibly special to retain the Ashes in England, something Australia have not done for 18 years.
"It feels amazing to know the urn is coming home," he told Sky Sports as the celebrations continued around him.
"I've been here a few times where things haven't quite gone our way. We haven't performed to the best of our ability in '13 and '15 but it was always one I wanted to tick off my bucket list to get the urn over here."
Australia's attack toiled long and hard all day after England had begun the day 18-2 chasing an unlikely 383 to win.
A stubborn ninth-wicket stand between Jack Leach and Craig Overton offered England faint hopes of surviving but part-time spinner Marnus Labuschagne removed Leach before Overton was trapped lbw by Josh Hazlewood.
"The boys were getting a bit tired out there but at the start of the day we thought we would have our eight chances and it proved to be the way. England fought incredibly hard and Overton was exceptional and showed great courage," Smith said.
Hazlewood said there had been some anxious moments as England dug in.
"The heart was definitely beating fast in that last couple of hours," he said. "When we got Jos (Buttler) I think we felt we had the time but it was a hell of a last couple of hours."
Australia captain Tim Paine said it had been an emotional triumph, especially after England had snatched victory from the jaws of defeat in the third Test at Headingley.
"The amount of work to retain the Ashes has been enormous and I'm really proud of this group and how we bounced back from Headingley," he said.
"The atmosphere at every ground has been unbelievable. The noise they make here and the passion they have for cricket makes this moment all the more special. We're thrilled. This is what we came here to do.
"We'll have a bloody good night tonight together and celebrate but we'll be back on deck next week. We want to win the Ashes 3-1."
England skipper Joe Root said he was proud of his team despite now not being unable to win back the Ashes.
"Another great Test match, but it's bitterly disappointing," he said. "From today's point of view, I am really proud.
"You learn a lot about your team. Everyone stood up and played bravely. We have seen some wonderful Test cricket and I expect the same at The Oval.
"We want to level the series. We have to pick ourselves up and turn up at The Oval."
The early age for first period is associated with many factors such as higher socio-economic status, obesity, nutritional status and general health
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