" And he made from one man every nation of mankind to live on all the face of the earth, having determined allotted periods and the boundaries of their dwelling place".E.S.V. ..Nations are mentioned here but nations are made of individuals. e.g. If Bert and Marg live in London, England and they don't go to church or read the Bible or have time for God, and Marg says to Bert, "Let's go and live in Spain it will do your chest good" and following this they move to Spain. .Is the length of Bert's life [an individual] an "allotted period" and the exact shape of his new home in Spain "the boundary of his dwelling place"?

First of all, in Acts 17:26 Paul is in fact interpreting certain events from the book of Genesis when he gets to this part of his speech. Paul's arguments as it pertains to this verse only make sense if Paul is interpreting Genesis literally and as actual history. More on this later.

I will divide this into the phrases that make up this verse and offer an explanation.

The first phrase in the version you selected (ESV) has this:

Acts 17:26a (ESV)
26 And he made from one man every nation of mankind to live on all the face of the earth

Since the ESV is based on the critical text the translators supplied a term in the phrase--man. According to the critical text the phrase is ἐξ ἑνὸς πᾶν ἔθνος ἀνθρώπων--from one every nation of mankind. The question is one what? I think the textual variant answers that question.

In the Byzantine text the phrase adds the word αἵματος (blood).

That is why you have it this way in the KJV

Acts 17:26a (KJV)
26 And hath made of one blood all nations of men for to dwell on all the face of the earth,

The key in either case is the word ἔθνος. It can be translated as "people" or as "nation." In modern language we speak of "people groups" that are tied to a common history and especially language. I think that idea fits ἔθνος very well.

That phrase sets the context for the rest of the verse. What Paul is talking about is the formation of nations or people groups from one (nation, man, or blood) it is all the same idea. I would argue that "the periods and boundaries" (ESV) or "the times before appointed, and the bounds of their habitation" can only be understood as applying to nations. Using a well known historical example is an excellent illustration -- the rise and fall of the Roman Empire. It was God who determined when they would arise as a nation and it is God who determined the extent of their size.

Your idea that by because nations are made of individuals that this also applies to individuals is an interesting one. I just don't think that this is what Paul had in mind at that moment in time. If this applied to individuals who live in a nation your argument breaks down when you think of it this way: If you are affecting the limitation of your days by moving to a nation then you would see a trend that everyone in that nation would live to the same age since they are limited by the appointed days of their nation. Of course, that doesn't occur on any nation on earth and it never has been the norm. In the next two verses I think you would have a better argument that Paul is speaking about individuals.

Acts 17:27-28
27 That they should seek the Lord, if haply they might feel after him, and find him, though he be not far from every one of us: 28 For in him we live, and move, and have our being; as certain also of your own poets have said, For we are also his offspring.

Of course God knows exactly how many days an individual will live on this earth. God even knows the number of hairs that we have on our head. He knows our comings and goings. Even more important is that He knows us and He cares about us too.

Finally what was Paul doing in Acts 17:26? I think he was commenting on or using a fact from the Bible as the basis for his argument. Paul is looking back to Genesis 11:1-9 and the events that took place at the tower of Babel.

To simplify the case I am not going to go through the who context of Genesis 11:1-9, just the start and the finish.

Genesis 11:1-9 (KJV)
1 And the whole earth was of one language, and of one speech. … 8 So the LORD scattered them abroad from thence upon the face of all the earth: and they left off to build the city. 9 Therefore is the name of it called Babel; because the LORD did there confound the language of all the earth: and from thence did the LORD scatter them abroad upon the face of all the earth.

Prior to Babel mankind was of one nation, or people group, with a common language. Implicit in this is also the fact that it was embodied by a single blood. It is interesting that while we now have nationalities, people groups, and languages we still have common blood. Blood knows no nationalities, it is the one universal thing in mankind. It is what makes us all of the single race of mankind.

Another question to ask relative to Genesis 11:8-9 is "was this a single act of scattering or does God continue to scatter men over the whole earth and to keep them divided?" I take the view that it began at Babel and it continues to this day. It will continue until the day that all the saved have resurrection bodies and I think we will be once again a single race, and also a single people with a single language. Since sin will have been eradicated there will no be a need to divide man as a means of drawing us to Him (Acts 17:27-28).

God is the Author and Sustainer

The way to interpret this with the Systematic Theology known as "God the Sustainer". This uses the hermeneutic of "a Bible-based SysTheo to interpret the Bible". Theology is a topic for Christianity.SE, but, inasmuch as they are based on the Bible, those frameworks can be used as Bible-to-Bible hermeneutics.

God "determines" circumstances and timing in our lives. Even Jesus said that he did not know the time of his own return, but that the Father determines those times.

Matthew 24:36 (NASB) (also Mark 13:32)

“But of that day and hour no one knows, not even the angels of heaven, nor the Son, but the Father alone.

Then, he expands on that theme, applying it to all of us in Acts, where your question arises...

Acts 1:7 (NASB)

He said to them, “It is not for you to know times or epochs which the Father has fixed by His own authority;

So, this also uses the hermeneutic of "first mention". Luke explained this as God being in control of timing right in the first chapter. Later, by chapter 17, where your question arises, we already have the framework with which to interpret it.

The rest of the New Testament writers were familiar with this Biblical theme of God the Sustainer. They follow Jesus's model and teach it in the Book of Acts, they teach it through the rest of the New Testament, and they had learned it throughout the Old Testament.

It comes down to using the Bible interpreting the Bible. That upholds the old wisdom that the best way to know what the Bible means is to know what else it says.

To answer your yes/no question at the very end, yes. God focuses on everything from nations and epochs (Acts 1:7) and on the individual, right down to the sparrow, right down to the hairs on your head.

Matthew 10:29-31 (NASB)

29 Are not two sparrows sold for a cent? And yet not one of them will fall to the ground apart from your Father. 30 But the very hairs of your head are all numbered. 31 So do not fear; you are more valuable than many sparrows.

Consider Bible verses that support the SysTheo of God as Sustainer:

Job 38:33 (NASB)

"Do you know the ordinances of the heavens,
Or fix their rule over the earth?

Proverbs 16:9 (NASB)

The mind of man plans his way,

But the Lord directs his steps.

Acts 17:28 (NASB)

for in Him we live and move and exist, as even some of your own poets have said, ‘For we also are His children.’

Colossians 1:17 (NASB)

He is before all things, and in Him all things hold together.

Hebrews 1:3 (NASB)

And He is the radiance of His glory and the exact representation of His nature, and upholds all things by the word of His power. When He had made purification of sins, He sat down at the right hand of the Majesty on high,

Hebrews 12:2 (NASB)

fixing our eyes on Jesus, the author and perfecter of faith, who for the joy set before Him endured the cross, despising the shame, and has sat down at the right hand of the throne of God.

Excellent article that would relate to the scenario you gave as an example: What does it mean that Jesus is the author and perfecter of our faith (Hebrews 12:2)?